3.6L ScienceofSpeed Engine (NA Stroker)

[greenberet]

Just to make sure we're all on the same page, different dynos measured Ponyboy's ITB'd 3.6L n/a NSX as putting out 355 to 377 WHEEL hp. Dynos in the US often measure stock 270 crank hp 5-speed NSXs as putting out 235 wheel hp so using that relationship, Ponyboy's NSX is probably putting out somewhere around 414 to 439 PS at the crank.

 

[naaman]

Well, engine response - both on and off throttle are certainly strong characteristics of the ITB setup. Pricing for the 3.6L stroker that I bought is around 15k and the ITBs are 5k. hp has ranged from 355 to 377 on mine on different dynos.

Just to be clear Shawn, you're talking wheel horsepower with those numbers, correct? And I've been wondering: do the prices on SOS's website include labor/installation? Or is that just parts? I've always assumed it was only giving the price for parts.

 

[Ponyboy]

My apologies…yes, I meant wheel hp. The prices listed are strictly for the product not including labor or any associated parts or tuning.

Hope to have some track vids up this summer.

 

[BATMANs]

How much does the ITB give on the low end response and power/TQ?

I'm curious since my understanding of the short intake runner on the ITB is optimized for high end power in relation to the port velocities, etc.

From what I've been told is that the M5 have longer intake runners that covers a wider range on the RPM.

 

[Ponyboy]

I think you'd really have to drive it in order to determine how you think low end response is affected. But in theory, b/c it doesn't take as long to fill each chamber with air, the low end is where you'd feel the most difference.

Shorter runners = torque peak at a higher RPM.
Longer runners = torque peak at a lower RPM.

Be nice to have a variable intake runner. That M5 engine bay looks like mine: Avus Blue w/ the crack on the plastic firewall trim piece.

 

[naaman]

How much does the ITB give on the low end response and power/TQ?

I'm curious since my understanding of the short intake runner on the ITB is optimized for high end power in relation to the port velocities, etc.

From what I've been told is that the M5 have longer intake runners that covers a wider range on the RPM.

I understand that the original dynos for the SOS ITB showed as much as an 82 lbs.ft gain in some areas, with peak torque being improved by 62 lbs.ft, and peak power improved by 41 whp. That car has since been tuned a few times and seen even more gains of as much as an additional 40-ish horsepower (the car, when I rode in it, made 274 whp. It was tuned again and managed 317 whp).

 

[nismor32gtr]

Awesome!!!! Is that a SOS build Shawn?

- - - Updated - - -

So anyone had a high compression 3.2 or 3.3 running around 11 to 1 or 11.5 to 1 compression with high lift cams built by SOS? That's what I'm looking for. I don't want to spend $20,000 for a 3.5 or 3.6L that requires heavy boring that will make is less reliable as a track engine. I like the response of the 3.0 and 3.2 and think it would be the best size for aight weight track car with good response and power. What do you think SOS would charge for a build like that?

 

[tbnsxt]

How much does the ITB give on the low end response and power/TQ?

I'm curious since my understanding of the short intake runner on the ITB is optimized for high end power in relation to the port velocities, etc.

From what I've been told is that the M5 have longer intake runners that covers a wider range on the RPM.

 

[Ponyboy]

You know, I understand rod ratio is an issue for some and that the stroker engines are right on that line of theoretical uncomfortableness. However, 3.5 to 3.9 C30-2 engines have been used in all from of motorsports and quite reliably. My engine has run at extremes and not one Blackstone analysis has shown excessive wear. IIRC, the old Comptech NSX used a high compression 3.0 to make about 400hp at the crank but it had to be rebuilt after every race.

Shoot, my next engine is going to be a 3.5 turbo.

I'd send an email over to Chris at SOS and see if he can put together a quote for you.

 

[nismor32gtr]

Lol well see that's the reason right there. 400hp from the 3.0 would require a lot of compression to achieve and on race fuel. That kind of strain would be insane. So a rebuild after every race would be smart. I'm not looking for 400hp from a 3.0, I would like 350-360 from a 3.2 that revs up fast has good response and is balanced to handle a beating. I will call him up and see what's what. I would hope a simple 3.2 build would cost less to build then a 3.6 so we will see. Thanks for the info

 

[scammy]

I have just bought a complete 3.2 block with pistons and had some spare heads ported and polished and installed SOS N/A cams and valves etc, SOS has assembled my parts with theirs and i should be shipping it over here soon so before this year is out i will be able to provide some comparisons between 3.0 with mods and a 3.2 with same mods plus the new head work. While i am waiting for the engine to arrive i will install a aftermarket ECU www.linkecu.com on my current setup and that will power the new engine as well. I did not go for different pistons so the block is all OEM just the head work will be different and all parts in the heads are WPC treated.

 

[nismor32gtr]

Will the head work raise the compression? The stock 10.2-1 is pretty low. I'd like to see 11.0-1 or 11.5-1 on pump gas 95 octane. I am curious to see how yours turns out after head work and cams with tuning. How much did you spend on the rebuild with cams and all. I I'm looking to do a build close to that. I plan to do the RDX injector upgrade and tuning and throttle body porting. I'd hope that with that and the C32B valves and angled valve job with minor porting and cams would be good for around 350bhp.

 

[scammy]

We should probably take this conversation off this thread my engine and what you are asking about is not a stroker, i have all those mods and some others but i doubt i will hit 350hp but that would be nice.

 

[BATMANs]

Ponyboy, I may have missed it somewhere but was there a change in compression and did you have any head work done like 3 angle valve job and/or porting?

 

[Ponyboy]

Apologies for the late reply. Compression is stock and the heads had SOS's competition valve job. Not sure if that was specifically a "3 angle" valve job.

The stock NSX heads flow pretty well from the factory.

 

[BATMANs]

Did you consider raising the CR to 12:1?

 

[Ponyboy]

Definitely. But, IMHO, the car is at it's sweet spot HP wise. I think the only thing necessary is moving back to a 4.06 instead of the 4.44 final drive.

 

[RYU]

Definitely. But, IMHO, the car is at it's sweet spot HP wise. I think the only thing necessary is moving back to a 4.06 instead of the 4.44 final drive.

Shawn, I can't remember if you have a 6spd but I think the 4.06 is a great idea if you have a 6spd or the JDM short gear 5spd. I'm really glad I kept my final drive stock in my CTSC but the short gears made all the difference. I have a JDM Type R transmission sitting in the garage but haven't found the need to install it.

I imagine your stroker is similar to Jon Martin's 3.8L NA i've driven. I think a 4.06 or even 4.23 (if you like shifting more) would be perfect imho.

God, I want a built NA motor...

 

[BATMANs]

If i did a 2nd NSX I would do a stroker with high CR pistons and short gears with a 4.44 final.

Just see how much all engine speed I can get.

 

[Ponyboy]

Shawn, I can't remember if you have a 6spd but I think the 4.06 is a great idea if you have a 6spd or the JDM short gear 5spd. I'm really glad I kept my final drive stock in my CTSC but the short gears made all the difference. I have a JDM Type R transmission sitting in the garage but haven't found the need to install it.

I imagine your stroker is similar to Jon Martin's 3.8L NA i've driven. I think a 4.06 or even 4.23 (if you like shifting more) would be perfect imho.

God, I want a built NA motor...

I agree, RYU. I do, in fact, have the JDM shorty 5 speed. The 4.23 is perfect for stock engine. For a stroker, the 4.44 is just too much torque multiplication down low for track work. IIRC, John's is at 320rwhp. I'm at 369rwhp and weighing a little over 2700lbs.

If i did a 2nd NSX I would do a stroker with high CR pistons and short gears with a 4.44 final.

Just see how much all engine speed I can get.

You should do it!

 

[BATMANs]

Think it may be an 11 sec all-engine-NSX?

 

[RYU]

Think it may be an 11 sec all-engine-NSX?

Lol not interested in a straight line car

 

[Ponyboy]

Think it may be an 11 sec all-engine-NSX?

IIRC, most online ¼ ET calculators estimate it at 11.3-4 seconds given weight and hp. But I find that suspicious at best b/c of a lack of other pertinent variables.

Lol not interested in a straight line car

It can be an interesting metric when viewed in combination with others.

 

[RYU]

It can be an interesting metric when viewed in combination with others.

Depending on the individual it certainly can be. However, I would argue the NSX is the wrong car for sheer WOT performance metrics which a 1/4 mile time is almost solely dependent on WOT performance for engine and drivetrain. I'd argue, there are certainly much better cars to buy for this type of user.

To me an NA motor is all about the linear and predictable performance at all other RPMs.

Anyway, just trying to pretend I don't have work to do.... back to it.

 

[Ponyboy]

You may be thinking too much in depth about it. IMHO, you're right in that the NSX isn't a ¼ mile specific machine. But ¼ mile times taken in combination with other performance metrics (0-60, 0-100, 60-0, 100-0, lateral g, lap times, passing speed, etc) make for a telling performance story that raises the interest for those so inclined. It's just one metric out of many.

What I like about the stroker and ITB combination so far is it's predictability (you're absolutely right), reliability, and tractability.

In a few years, after my Ph.D work is done, I'd love to build a variable length ITB system a la the Mazda 787B.