Nissan GTR question

"TheHondaBro" (wwaveform) 10/07/2015 at 11:20 • Filed to: None

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Does anyone know how much power the R35 GTR makes without the turbos? I’m curious.

cletus44 aka Clayton Seams > TheHondaBro 10/07/2015 at 11:22

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Someone Else's Projects > TheHondaBro 10/07/2015 at 11:26

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Considering it only has a 9:1 compression ration while the naturally aspirated VQ is 11:1, it’s a difficult comparison. Just taking off the turbos and replacing them with dummy pipes is really unfair to an engine purpose-designed for a forced induction application.

TheHondaBro > Someone Else's Projects 10/07/2015 at 11:29

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Interesting. For the most part, I’m clueless when it comes to forced induction.

66671 - 200 [METRIC] my dash > TheHondaBro 10/07/2015 at 11:30

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I thought about this but with the Veyron.

Future next gen S2000 owner > TheHondaBro 10/07/2015 at 11:32

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No, because the GTR doesn’t come naturally aspirated. The motor architecture may be shared with other cars but they are built and designed very differently.

It would probably be a dog though. Low compression, low displacement and high weight are bad together.

KnowsAboutCars > TheHondaBro 10/07/2015 at 11:37

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Not really answering your question but Gibson Technology has built 500 hp naturally aspirated racing version of the VR38.

EDIT: forget that apparently it’s still twin turbo engine they just called it ‘DE’ instead of ‘DETT’ on their page.

Highlander-Datsuns are Forever > TheHondaBro 10/07/2015 at 11:38

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The old 300 zx was 222 hp NA, and 300 turbo, so that’s a 26% reduction in HP, but I think those motors were pretty much identical, one with turbo’s and one without. Like Lab Coat guy said, they are so specific for turbo now it’s kinda not relevant.

Someone Else's Projects > TheHondaBro 10/07/2015 at 11:44

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So going back to even the early days of automotive forced induction, it usually took some internal revisions, almost always including lower compression ratio, to “convert” a naturally aspirated engine into a turbocharged one while retaining reliability; the Saab 99 and BMW 2002 both had to do this. For the Jaguar AJ-V8, the supercharged version even lost the variable valve timing that the N/A versions had, as it didn’t make enough of a difference in power when the air coming into the engine was already compressed. Basically, N/A and forced induction engines are pretty different due to NA-specific vs. forced induction specific parts even if they’re in the same engine family.

That being said, it would be easier to compare a supercharged vs. turbocharged version of an engine, as they should be based on similar internals, but there aren’t many engine families that have both supercharged or turbocharged versions.

crowmolly > TheHondaBro 10/07/2015 at 11:47

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Compression ratio is the thing here. Without getting too much into static vs. dynamic, timing, short block design and such, the big takeaway is that forced induction engines have typically lower compression ratios to allow for boost, and in an NA engine less compression = less power.

An example is the GM 3800s from the 90s.

NA 3800 = ~ 200hp/230tq at 9.4:1 compression

S/C 3800 = ~ 240 hp/280 tq at 8.5:1 compression

If you yank the belt off of the supercharged engine it makes less than the NA version by a non-trivial amount. If you throw the supercharger setup on the NA engine you will scatter parts.

Someone Else's Projects > crowmolly 10/07/2015 at 11:53

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If you throw the supercharger setup on the NA engine you will scatter parts.

And to build on that (pun not intended but not repudiated), the Oldsmobile experiments with turbocharging in the 60s retained the high 10.25:1 compression ratio of the NA engine, but they had serious problems with knock issues that required adding on a methanol water injection setup to cool down the intake charge.

Wacko > TheHondaBro 10/07/2015 at 11:57

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remove turbos??

replace with a n/a 3.5 VQ, then should make about 260 hp

Roman Savchuk > TheHondaBro 10/07/2015 at 12:00

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Removing wastegate actuators so that wastegate valves could swing wide open would give like what... 2-3psi max boost? which is almost NA. Dyno it somewhere at altitude and you’ll get pretty accurate whp numbers)))

BigBlock440 > crowmolly 10/07/2015 at 12:12

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With everything I’ve heard of the 3800, I’m not sure you would scatter parts, but you certainly wouldn’t be able to run 87 anymore.

crowmolly > BigBlock440 10/07/2015 at 12:17

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Yeah, that was a bit of hyperbole. You do hit KR issues faster though. Pretty much all the people I’ve seen who did an L67 top end onto an L36 have also cut down the boost they are running. The “kits” include a larger blower pulley than stock.

Galileo Humpkins (aka MC Clap Yo Handz) > TheHondaBro 10/07/2015 at 13:31

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Not enough.

AMGtech - now with more recalls! > TheHondaBro 10/07/2015 at 16:09

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Considering what everyone else already talked about... I don’t know anything about R35’s or Nissans, but I will give you another example.

Consider a CLA250 with its turbo 2.0L at 208hp. I think I can safely assume a non-turbo variant would produce around 170hp. Then you have the CLA45 making 355. All more or less the same thing, you still get an enormous gap.

Or the M152 used in the current SLK55 at 421hp, from an NA 5.5L V8 that is basically the same as the engine in the SL63, the M157 at 577hp.

So... Anywhere from 15-75% difference?

Sweet Trav > TheHondaBro 10/07/2015 at 16:35

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The short and sweet of it is for every 14.7 PSI you put down a motor you double its output.

Tikigod > Highlander-Datsuns are Forever 10/07/2015 at 19:00

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The VG30DE and VG30DETT had different compression ratios, 10.5:1 for the NA and 8.5:1 for the TT.