Adjustable cam gears

[jaffaz32]

Would you install adjustable cam gears when building a low comp motor for boost?

Trying to justify the expense. Worth stretching the budget for?

 

[jaffaz32]

I was reading that when doing a full motor build it is good practice to install adjustable cam gears because the gap between the cams and crank pulley changes because of head/block skimming or different thickness gaskets.

Adjustable cam gears will allow you to dial it back in to factory specs.

I don't think i'm using them to advance or retard the timing as far as i'm aware this is all done within the ecu unless that refers to ignition?

 

[stuntman]

If you're building a motor and have someone who knows how to adjust them, its worth it to make some power, and make the engine not 'work' as hard by synchronizing the front and rear banks.

 

[Mac Attack]

Would you install adjustable cam gears when building a low comp motor for boost?

Trying to justify the expense. Worth stretching the budget for?

Not in my opinion. Think about it this way - you'd be spending about $1500 extra (the gears plus time spent adjusting them) for an ~30WHP gain in a narrow part of the rev band.

Also, if you don't do it yourself, then you REALLY need to trust the engine builder not to screw them up. To properly get the most out of them, you need to degree the cams, verify valve-valve and piston-valve clearances, and then adjust them to verify gains on a dyno. It's time-consuming to adjust while on a dyno since the valve covers have to come off, or you need to modify your OEM magnesium covers (i.e. more money).

You shouldn't be decking the block or heads that much where you change the geometry of the front-rear bank appreciably. We're talking about thousandths of an inch difference on a ~4 inch diameter cam gear arc that translates into what - 0.1 degrees? You'll get more variance when you go to torque the adjustable cam gears.

The block and heads should only be polished to the surface roughness your MLS gasket maker requires for a good seal. It shouldn't remove much material at all. Just pay attention to how much is removed and make up that difference with a custom HG if you really need to. Unfortunately, a bad initial machinist touched my block and took off more than I wanted. In order to maintain the correct squish and P2V clearance, I went with a custom Cometic HG. I measured everything.

To get additional power throughout the entire rev band), you need variable cam timing like the new cars have. Unfortunately, I know of only a handful of people who have modified such systems onto older engines like ours.

My engine makes the most torque of any other FI'd NSX from ~2000 to ~3900 RPM. I taper it off after that to still achieve ~500 WHP. That was done with a fancy turbo setup though and not aftermarket cams or cam gears that can be a PITA to setup.

My $.02.

Dave

 

[stuntman]

^Dyno sheet / turbo specs?

 

[jaffaz32]

Not in my opinion. Think about it this way - you'd be spending about $1500 extra (the gears plus time spent adjusting them) for an ~30WHP gain in a narrow part of the rev band.

Also, if you don't do it yourself, then you REALLY need to trust the engine builder not to screw them up. To properly get the most out of them, you need to degree the cams, verify valve-valve and piston-valve clearances, and then adjust them to verify gains on a dyno. It's time-consuming to adjust while on a dyno since the valve covers have to come off, or you need to modify your OEM magnesium covers (i.e. more money).

You shouldn't be decking the block or heads that much where you change the geometry of the front-rear bank appreciably. We're talking about thousandths of an inch difference on a ~4 inch diameter cam gear arc that translates into what - 0.1 degrees? You'll get more variance when you go to torque the adjustable cam gears.

The block and heads should only be polished to the surface roughness your MLS gasket maker requires for a good seal. It shouldn't remove much material at all. Just pay attention to how much is removed and make up that difference with a custom HG if you really need to. Unfortunately, a bad initial machinist touched my block and took off more than I wanted. In order to maintain the correct squish and P2V clearance, I went with a custom Cometic HG. I measured everything.

To get additional power throughout the entire rev band), you need variable cam timing like the new cars have. Unfortunately, I know of only a handful of people who have modified such systems onto older engines like ours.

My engine makes the most torque of any other FI'd NSX from ~2000 to ~3900 RPM. I taper it off after that to still achieve ~500 WHP. That was done with a fancy turbo setup though and not aftermarket cams or cam gears that can be a PITA to setup.

My $.02.

Dave

Thanks for the info, that all makes sense now it's been explained, saved me a considerable amount of money. Thanks.

- - - Updated - - -

If you're building a motor and have someone who knows how to adjust them, its worth it to make some power, and make the engine not 'work' as hard by synchronizing the front and rear banks.

My engine builder builds allot of race engines, he's not built a Nsx motor before.

I wouldn't need to make anymore power, I'm sleeving the block and putting in low comp Pistons, I'm more than likely installing a stroker kit and with the gtx turbo I wouldn't be needing any extra power the gears may provide.

Probably best I don't overly complicate things and push up my build costs with the builder.

 

[stuntman]

Low compression will make the off boost response lazy. Stroker will help... Cam gears allow the front and rear banks to be synchronized and more efficient rather than fighting each other like the car does stock. Do what the budget allows.

 

[jaffaz32]

Low compression will make the off boost response lazy. Stroker will help... Cam gears allow the front and rear banks to be synchronized and more efficient rather than fighting each other like the car does stock. Do what the budget allows.

I went with a 9.2:1 piston, the stroker is the Brian Crower 2.4L kit. Confirmed the order, waiting on parts prior to shipping. The specs on the site say it's a 84mm stroke vs 78mm of the factory setup. Not sure what difference 6mm makes.

 

[Mac Attack]

^Dyno sheet / turbo specs?

The dyno sheet has been posted near the end of my engine build thread. The layout, turbos, and specifications are proprietary for now.

- - - Updated - - -

Low compression will make the off boost response lazy. Stroker will help... Cam gears allow the front and rear banks to be synchronized and more efficient rather than fighting each other like the car does stock. Do what the budget allows.

How do the OEM cam gears make the front and rear banks fight each other? Honda engineers optimized the valvetrain and timing taking into account all of the production tolerances.

There is no free ride - you either optimize parameters in one area and take a sacrifice in another area... unless you have the VCT system retrofitted as I've discussed earlier and in separate threads.

- - - Updated - - -

I went with a 9.2:1 piston, the stroker is the Brian Crower 2.4L kit. Confirmed the order, waiting on parts prior to shipping. The specs on the site say it's a 84mm stroke vs 78mm of the factory setup. Not sure what difference 6mm makes.

Awesome - That will be a lot of fun!

 

[stuntman]

Link?

"Proprietary"? Are you racing competitively?

 

[greenberet]

Would you install adjustable cam gears when building a low comp motor for boost?

If you haven't read it yet, have a look at what DAL Motorsports wrote about adjustable cam gears in NSXs here. DAL hints at modifying the valve overlap when going forced induction, which could be an interesting topic to look into. I never did because my NSX is naturally-aspirated.

I fully agree with Mac Attack that you should use an engine builder you really trust. My shop is going to drop my NSX's engine again to readjust the cam gears because it seems they screwed up the first time around. Without causing any engine damage, thank God.

 

[jaffaz32]

have I picked the correct combo?

As Stuntman mentions low comp builds are lazy off boost.

I have a element of doubt in my mind now.

9.2:1 compression with the 3.4L 84mm stroke? Aiming for 540WHP

How would my setup respond off boost? Is it too low comp? I tried to spec it with lots of safety and reliability

I have a GTX30 series turbo, so spool time is low rpm, possibly even lower with an stroker.

Excited and bricking it at the same time.

 

[Mac Attack]

have I picked the correct combo?

As Stuntman mentions low comp builds are lazy off boost.

I have a element of doubt in my mind now.

9.2:1 compression with the 3.4L 84mm stroke? Aiming for 540WHP

How would my setup respond off boost? Is it too low comp? I tried to spec it with lots of safety and reliability

I have a GTX30 series turbo, so spool time is low rpm, possibly even lower with an stroker.

Excited and bricking it at the same time.

You went with a stroker setup because of the unknown status of your OEM crank, right? There was an oil pressure problem IIRC.

The only reason to go with low static compression pistons is if you are applying a lot of boost to a small engine in order to obtain a lot of power. In that case, it is easier to cool the compressed intake charge before it goes into the engine with an intercooler than it is to cool the intake charge after it is compressed inside of the combustion chamber. 550 WHP is a lot, but not THAT high. I personally think you'd be fine with OEM compression for this case. If, in the future, you decide to go back to N/A or decide to sell your car, the engine would probably be more desirable if it had the OEM 10.2:1 compression... for the reason Stuntman gave.

HOWEVER, you are going all out on this engine. It is being built to handle a lot more than 550 WHP. It's an understatement that power is addictive, and I imagine you will want to bump it up later down the road with additional boost. In that case, keep to your original plan with the low compression pistons.

My $0.02.

Dave

- - - Updated - - -

If you haven't read it yet, have a look at what DAL Motorsports wrote about adjustable cam gears in NSXs here. DAL hints at modifying the valve overlap when going forced induction, which could be an interesting topic to look into. I never did because my NSX is naturally-aspirated.

I fully agree with Mac Attack that you should use an engine builder you really trust. My shop is going to drop my NSX's engine again to readjust the cam gears because it seems they screwed up the first time around. Without causing any engine damage, thank God.

I was thinking about him when I wrote the above... but for the reason that he destroyed that engine while adjusting the gears on the dyno!

I'm sorry to hear about your engine. Just curious what gave it away? Driveability issues?

 

[Stephen@NCAutoUSA]

have I picked the correct combo?

As Stuntman mentions low comp builds are lazy off boost.

I have a element of doubt in my mind now.

9.2:1 compression with the 3.4L 84mm stroke? Aiming for 540WHP

How would my setup respond off boost? Is it too low comp? I tried to spec it with lots of safety and reliability

I have a GTX30 series turbo, so spool time is low rpm, possibly even lower with an stroker.

Excited and bricking it at the same time.

Who is building your motor? Do you have a reputable shop doing the work?

 

[RYU]

Don't forget your other supporting components. I'm sure you're already asking yourself questions like.. Can my transmission handle all this extra power based on how you drive your car..

 

[greenberet]

Just curious what gave it away? Driveability issues?

No, I didn't notice any driveability issues whatsoever. Perhaps my idle is very slightly lumpier in the direction of an American V8 engine, but I like that.

During the dyno runs after my Comptech cam gears were installed, my NA1 five speed put 26.8% more power to the wheels than a bone stock NA1 five speed that came along as a reference. However, my car showed a strange torque dip at about 3500 rpm. A few months later, we went to a different facility and during those dyno runs, the torque dip at 3500 rpm was still there but this time, my NSX put out barely more horsepower than the stock NSX did.

To find out what was going on, I had the exhaust gases analyzed and the compression checked. The exhaust gases were all screwed up and my rear bank of cylinders had a very even 1/3 less compression than the front bank. I had a leak-down test performed and the results were the same for all the cylinders so there's no problem with piston ring, intake, or exhaust valve sealing. The leak-down test and a coolant analysis indicated no problem with the cylinder head gasket. What's left over is that the timing of the camshafts for the rear bank of cylinders is probably screwed up.

I measured the stability of the vacuum in the intake plenum at idle and that looks good so I'd guess that the exhaust camshaft for the rear bank is off. If that's the case, it's amazing the exhaust valves didn't hit anything.

In any case, since the cam gears are so hard to get to, the engine has to be dropped again to check and most likely readjust their timing. I like the idea of adjustable cam gears but they do introduce a new area where something expensive can go wrong. If you want to install some adjustable cam gears in your NSX, make sure the work is carried out by someone you really trust!

 

[jaffaz32]

You went with a stroker setup because of the unknown status of your OEM crank, right? There was an oil pressure problem IIRC.

The only reason to go with low static compression pistons is if you are applying a lot of boost to a small engine in order to obtain a lot of power. In that case, it is easier to cool the compressed intake charge before it goes into the engine with an intercooler than it is to cool the intake charge after it is compressed inside of the combustion chamber. 550 WHP is a lot, but not THAT high. I personally think you'd be fine with OEM compression for this case. If, in the future, you decide to go back to N/A or decide to sell your car, the engine would probably be more desirable if it had the OEM 10.2:1 compression... for the reason Stuntman gave.

HOWEVER, you are going all out on this engine. It is being built to handle a lot more than 550 WHP. It's an understatement that power is addictive, and I imagine you will want to bump it up later down the road with additional boost. In that case, keep to your original plan with the low compression pistons.

My $0.02.

Dave

- - - Updated - - -



I was thinking about him when I wrote the above... but for the reason that he destroyed that engine while adjusting the gears on the dyno!

I'm sorry to hear about your engine. Just curious what gave it away? Driveability issues?

That is correct, Because i live in the UK i didn't want to order the parts i needed on the assumption that the crank would be ok, then to wait until the engine shop pull apart my motor to realize i need a new crank to put the build on hold and have to order more parts. I decided just to replace the crank.

That is right but... my car felt savagely fast before, with a extra 150bhp would i ever need more?

I now have doubt thinking i should have maybe gone for a 9.5:1 or even closer to factory compression. I'm not sure what difference this makes but i also have Darton sleeves going in.

- - - Updated - - -

Who is building your motor? Do you have a reputable shop doing the work?

It's a local engine shop, they do allot of race engine for different series here in the UK. He's not built a Nsx engine before, but not many have in the UK.

http://www.damico-engines.co.uk/

- - - Updated - - -

Don't forget your other supporting components. I'm sure you're already asking yourself questions like.. Can my transmission handle all this extra power based on how you drive your car..

I think i've got most stuff covered with the exception of the brakes.

I've got a ATS LSD, DriveShop Axles, BC Coilovers, SOS Carbon clutch, Darton sleeves, AEM Infinity, Koyo Rad, loads other bits n bobs, hard to keep track.

But yes, my 5 speed box is stock so i don't want to be pushing numbers too much.

 

[Mac Attack]

No, I didn't notice any driveability issues whatsoever. Perhaps my idle is very slightly lumpier in the direction of an American V8 engine, but I like that.

During the dyno runs after my Comptech cam gears were installed, my NA1 five speed put 26.8% more power to the wheels than a bone stock NA1 five speed that came along as a reference. However, my car showed a strange torque dip at about 3500 rpm. A few months later, we went to a different facility and during those dyno runs, the torque dip at 3500 rpm was still there but this time, my NSX put out barely more horsepower than the stock NSX did.

To find out what was going on, I had the exhaust gases analyzed and the compression checked. The exhaust gases were all screwed up and my rear bank of cylinders had a very even 1/3 less compression than the front bank. I had a leak-down test performed and the results were the same for all the cylinders so there's no problem with piston ring, intake, or exhaust valve sealing. The leak-down test and a coolant analysis indicated no problem with the cylinder head gasket. What's left over is that the timing of the camshafts for the rear bank of cylinders is probably screwed up.

I measured the stability of the vacuum in the intake plenum at idle and that looks good so I'd guess that the exhaust camshaft for the rear bank is off. If that's the case, it's amazing the exhaust valves didn't hit anything.

In any case, since the cam gears are so hard to get to, the engine has to be dropped again to check and most likely readjust their timing. I like the idea of adjustable cam gears but they do introduce a new area where something expensive can go wrong. If you want to install some adjustable cam gears in your NSX, make sure the work is carried out by someone you really trust!

I wasn't aware you had dyno'd the new configuration. Again, sorry to hear about that but it certainly could have been worse. Hope it works out the second time. I would ensure they do the compression test again before reinstalling the engine.

- - - Updated - - -

That is correct, Because i live in the UK i didn't want to order the parts i needed on the assumption that the crank would be ok, then to wait until the engine shop pull apart my motor to realize i need a new crank to put the build on hold and have to order more parts. I decided just to replace the crank.

That is right but... my car felt savagely fast before, with a extra 150bhp would i ever need more?

I now have doubt thinking i should have maybe gone for a 9.5:1 or even closer to factory compression. I'm not sure what difference this makes but i also have Darton sleeves going in.

I would talk with your engine builder and tuners then for their professional input. They can provide some guidance based on your goals.

Personally, if you aren't going over 550WHP, I would do 10.2:1 static CR with your stroker. That's what I did on my 500WHP build. If you can see yourself going higher than 550WHP someday, I would stick with the lower CR pistons.


Is the ATS LSD new or have you had it installed for awhile now? I'm curious on your feedback please since I am considering one too (probably the carbon version). You've had the SOS twin carbon clutch for awhile too, right? Has that been holding up well?

Sorry to get too much off-topic, but did you check into the Timeserts for your engine block as well as a new oil cooler (or at least THOROUGHLY cleaned)?:
http://www.nsxprime.com/forum/showthread.php/191322-Engine-rebuild-recomendations-gaskets?

 

[stuntman]

Where's your motor build thread & dyno Mac?

 

[RYU]

It's the gearbox that worries me. Particularly 2nd and 3rd gear. [MENTION=4034]Coz[/MENTION] has had his fair share of stripping the teeth of gears. Again, it depends how you plan to drive the car as he tracks his car on slicks regularly.

Also, just to reiterate on the adjustable cam gears. They seem impossible to adjust while the engine is in the car. So unless you're tuning on an engine dyno it seems unpractical from a tuning standpoint.

 

[jaffaz32]

I wasn't aware you had dyno'd the new configuration. Again, sorry to hear about that but it certainly could have been worse. Hope it works out the second time. I would ensure they do the compression test again before reinstalling the engine.

- - - Updated - - -



I would talk with your engine builder and tuners then for their professional input. They can provide some guidance based on your goals.

Personally, if you aren't going over 550WHP, I would do 10.2:1 static CR with your stroker. That's what I did on my 500WHP build. If you can see yourself going higher than 550WHP someday, I would stick with the lower CR pistons.


Is the ATS LSD new or have you had it installed for awhile now? I'm curious on your feedback please since I am considering one too (probably the carbon version). You've had the SOS twin carbon clutch for awhile too, right? Has that been holding up well?

Sorry to get too much off-topic, but did you check into the Timeserts for your engine block as well as a new oil cooler (or at least THOROUGHLY cleaned)?:
http://www.nsxprime.com/forum/showthread.php/191322-Engine-rebuild-recomendations-gaskets?

Aw in which case I better stick with the compression ratio, I say at this time I will cap it at 550whp but there is currently a thread regarding development of a new gear set for the 5 speed. Maybe down the line if I get that itch I have the option there.

The ATS Lsd I have was one of my first mods, I did it because it came with a different pinion gear, quick fix for faster acceleration. I have the carbon version, probably installed for about 3 years maybe more. Not any issues yet, my car didn't see that many miles boosted to be fair. Seen a couple of track days. Holding up well.

I have had the clutch a couple of years, I had to send it off to be rebuilt, to this date I can't be sure of the cause of the excessive wear, installation, use or the clutch itself. Cody has an alternative solution that holds similar power levels. I wouldn't rebuild it a second time if it happens again.

I mentioned to my engine builder at the time about time inserts after reading a post on prime, he seemed glued up on it.

I'll check out the thread, the oil cooler I havnt given a thought. I'll perhaps remove it before it goes in to clean it so it gets cleaned twice, especially seeing my oil issues. I did have a external oil cooler installed but here in the uk it doesn't really get that hot, I'm considering leaving it off to simplify the oil system. I can install a sensor and set a safety parameter in the aem to cut the revs if needed.

- - - Updated - - -

It's the gearbox that worries me. Particularly 2nd and 3rd gear. [MENTION=4034]Coz[/MENTION] has had his fair share of stripping the teeth of gears. Again, it depends how you plan to drive the car as he tracks his car on slicks regularly.

Also, just to reiterate on the adjustable cam gears. They seem impossible to adjust while the engine is in the car. So unless you're tuning on an engine dyno it seems unpractical from a tuning standpoint.

Is yours a 5 or 6 speed? I hear the 5 speed have thicker gears, not sure how much truth is in that.

That's a good point, the tuner does actually have an engine dyno, if he is able to hook up my setup or not I don't know. Not sure how that works if he can only plug In what he has adapters for if they do it a different way.

 

[RYU]

The 5spd is stronger but in the case with [MENTION=4034]Coz[/MENTION] he was stripping 2nd and 3rd on the 5spd. Not the 6spd. WPC treatment adds additional strength apparently so perhaps you can look into that as well.

 

[Coz]

Yes, I've broken a few 2nd & 3rd gears, not to mention a ring and pinion. Always managed shaved most the teeth off of whatever every time.

Its a balance of Torq, Clutch, Grip and even Motor Mounts that either keeps a gearbox intact to something gives.
Too much clutch applied wrong, not enough motor mount to hold the impact, too much grip, too much boost that comes on with torq, 2nd and 3rd gear are the issues. Constant pounding when all else is right becomes a ring and pinion issue.

Coatings help, but they change the specs and eventually it wears a way anyway, clearances change and in the end, means nothing.
I have WPC'd 2nd, 3rd, 4th and the ring and pinon, including my OS 4.40. When you take them a part, they all look great...in the places that don't wear. The places they do, they are right back to wearing on the materiel that was there to begin with and any coating you put on is gone. If anything, you need to harden the pieces, shot preening for an example.... but in the end, to hard, they become brittle and break anyway due to heat, age and fatigue.

Its a balance of torque, clutch, grip and how it hooks up, where the shock goes and how that shock is supported. Get it wrong and something breaks. Every situation is different and needs to be supported differently.

Its as simple as that, Life is a balance, so are gearboxes .....

- - - Updated - - -

Just to name a few
This is 3 different occasions.

- - - Updated - - -

Two more for the hell of it that made me cringe

 

[greenberet]

Also, just to reiterate on the adjustable cam gears. They seem impossible to adjust while the engine is in the car. So unless you're tuning on an engine dyno it seems unpractical from a tuning standpoint.

+1

If you're interested in adjusting cam gears on an engine dyno, there was a discussion about that in this thread. Basically, it's not a trivial undertaking.

In that link to DAL Motorsports above, they mentioned that "I have seen as much as an 8degree variance between cams, and 6 degrees from where the centerline should be." If that's true, it's not good. Even if you don't spend days on an engine dyno finding your individual engine's camshaft timing sweet spot, you can make sure your cam timing is where the Service Manual says or your gut guesses it should be. As long as nothing gets screwed up during installation.

 

[jaffaz32]

Yes, I've broken a few 2nd & 3rd gears, not to mention a ring and pinion. Always managed shaved most the teeth off of whatever every time.

Its a balance of Torq, Clutch, Grip and even Motor Mounts that either keeps a gearbox intact to something gives.
Too much clutch applied wrong, not enough motor mount to hold the impact, too much grip, too much boost that comes on with torq, 2nd and 3rd gear are the issues. Constant pounding when all else is right becomes a ring and pinion issue.

Coatings help, but they change the specs and eventually it wears a way anyway, clearances change and in the end, means nothing.
I have WPC'd 2nd, 3rd, 4th and the ring and pinon, including my OS 4.40. When you take them a part, they all look great...in the places that don't wear. The places they do, they are right back to wearing on the materiel that was there to begin with and any coating you put on is gone. If anything, you need to harden the pieces, shot preening for an example.... but in the end, to hard, they become brittle and break anyway due to heat, age and fatigue.

Its a balance of torque, clutch, grip and how it hooks up, where the shock goes and how that shock is supported. Get it wrong and something breaks. Every situation is different and needs to be supported differently.

Its as simple as that, Life is a balance, so are gearboxes .....

- - - Updated - - -

Just to name a few
This is 3 different occasions.

- - - Updated - - -

Two more for the hell of it that made me cringe

That's very interesting you mention mounts not being stiff enough. I know STMPO used to make aftermarket solution and SOS currently still do but also innovative make engine mounts for our cars, you have a choice of different stiffness also. There was a article on Prime that they wasn't the best fit but this was dated back a couple of years ago, maybe they have improved.

PPG used to make a gear kit for our cars, not sure if they still do. Quaife also make an adaptor plate to fit one of their boxes but their boxes are big money.

What power level are you running at?

- - - Updated - - -

+1

If you're interested in adjusting cam gears on an engine dyno, there was a discussion about that in this thread. Basically, it's not a trivial undertaking.

In that link to DAL Motorsports above, they mentioned that "I have seen as much as an 8degree variance between cams, and 6 degrees from where the centerline should be." If that's true, it's not good. Even if you don't spend days on an engine dyno finding your individual engine's camshaft timing sweet spot, you can make sure your cam timing is where the Service Manual says or your gut guesses it should be. As long as nothing gets screwed up during installation.

Sorry to hear about your troubles, do you think you will be up and running by May? I'm hoping to make a trip to the ring. I think your closer than I am.


My engine shop has told me to get the cam gears if i can, he said they will offer no added reliability, my engine will run without them but it will run a load better with them. I think going by that he is comfortable installing them, he has the added bonus of the engine dyno, they are also lighter.

- - - Updated - - -

I wasn't aware you had dyno'd the new configuration. Again, sorry to hear about that but it certainly could have been worse. Hope it works out the second time. I would ensure they do the compression test again before reinstalling the engine.

- - - Updated - - -



I would talk with your engine builder and tuners then for their professional input. They can provide some guidance based on your goals.

Personally, if you aren't going over 550WHP, I would do 10.2:1 static CR with your stroker. That's what I did on my 500WHP build. If you can see yourself going higher than 550WHP someday, I would stick with the lower CR pistons.


Is the ATS LSD new or have you had it installed for awhile now? I'm curious on your feedback please since I am considering one too (probably the carbon version). You've had the SOS twin carbon clutch for awhile too, right? Has that been holding up well?

Sorry to get too much off-topic, but did you check into the Timeserts for your engine block as well as a new oil cooler (or at least THOROUGHLY cleaned)?:
http://www.nsxprime.com/forum/showthread.php/191322-Engine-rebuild-recomendations-gaskets?

The engine builder said he wouldn't work with a compression ratio higher than 9.2:1 on my build. I think he wants to cover himself with lots of safety, he said it might be a little lazy off boost but i will easily make that back up when in boost plus with the turbo spooling low rpm. he said it will only make a small difference to the power off boost but make a huge difference to the reliability on boost. I'm happy with that statement as it feels me with confidence that he wants to make sure it's a good strong build.