The 8500+ rpm question

[BlackMagik]

Has anybody seen a sho run 8500+ rpms??
I'm asking because of this response that I wrote to another post:


"Okay, I'm going to go out on a limb here so please don't tear me apart for doing this....

HP = (Torque X RPM)/5252

Assuming that the 3.2 makes roughly 186 lb-ft of torque at 6200 rpm (roughly where the max hp is)...and assuming that this torque is constant up to our hypothetical 300 HP....we would need to crank out about 8500 rpms to achieve 300 HP.

Solving for RPM = HP(5252)/T = 300(5252)/186 = about 8500 rpm.

So, if the original engine was designed to run at 8500 or above rpms, this engine, (theoretically) could make 300 hp as is with a higher rev-limiter.

HAVE FUN WITH THIS! BUT PLEASE REMEMBER THAT THERE ARE MANY VARIABLES UNACCOUNTED FOR SO TAKE THIS WITH A GRAIN OF SALT!!! "
--------------------
94 Emerald Green SHO completely stock
98 Ebony SHO with polished stainless Magnaflows with rolled oval tips
2002 1/2 Suzuki Hayabusa Midnight Falcon GSX1300R

 

[luigisho]

I believe the torque curve starts to drop before you get to the normally set redline already.

 

[jthomas68]

The average torque curve falls off under 7k rpms.It`s seen on a dyno and can be felt.The motor itself can easily run to 8500,but there isn`t any more power to be had.The 300hp is UNTRUE,why is there so many posts about it lately?

 

[drivinhard]

The intake and cams are well past breathing at that point, my 3.2L made a peak of 215 ft/lbs at the wheels, but only about 140 ft/lbs at 7300 rpm. It falls off fast after 6500 rpm or so. You are making 1.6L Honda torque at 8500 rpm.

 

[X-15 SHO]

You never know it can pop right back up. A little drop doesn't mean nothing. The question is will the accessories hold up?

 

[Dr.Evil]

You never know it can pop right back up. A little drop doesn't mean nothing.

It means the engine is past its powerband. It will not pick back up once it drops off, unless you add a third intake stage and hotter cams. This is true for almost all engines out there.

 

[Yamaha V6]

This is not a "little" drop Mark's talking about. Here's a typical SHO dynograph.

 

[jelloslug]

Since this is all theoretical talk anyway, could Yamaha have made a different intake and cam setup to move the powerband higher in the rpms? To some extent thats what happens with the various stages of cams and extruded and honed runners. If they had made a totally different intake with different runners tuned for even higher RPM is could be possable I guess.

 

[X-15 SHO]

Yamaha V6, gottcha now. I never knew it was that damn big off a drop. I can't tell when driving though.

Jelloslug, there is some talk about YAMAHA having different cams in there. wink

 

[Dr.Evil]

Here's an idea...Maybe they originally had say a 3.8L block with a little hotter cams and the same intake. 300 would be pretty easy. As they say, there is no replacement for displacement! thumbs_u

 

[LI_SHO]

What is the stock compression ratio of the SHO 3.0 motor?

 

[X-15 SHO]

9:8.1 or something like that.

 

[LI_SHO]

If you mean 9.8:1, then just hear me out...

Cars like the acura rsx-s, celica gts, and the like make most of their horsepower through a combination of high revs, and sky-high compression ratios (the rsx-s is 11:1 if i remember properly).

How feasible would is be to have custom forged higher compression pistons for the 3.0 or 3.2 motors, which IMO would be best matched for our n/a motor?

any input would be appreciated

 

[luigisho]

Welcome to a long time ago. They're already out there.

 

[LI_SHO]

luigisho:
Welcome to a long time ago. They're already out there.

then why arent people using them?
a LITTLE more info would be appreciated...

 

[cmichaelo]

reviving olddd thread about high comp pistons

Yeah, why aren't people using high compression pistons?

Some people seem to think you could throw in 11:1 in the SHO. Others don't, due to detonation and demands to very high octane gas.

Who's actually running high-compression pistons and do you use the car mainly for track or street?

Michael

 

[sho_sc]

Yeah, why aren't people using high compression pistons?

Some people seem to think you could throw in 11:1 in the SHO. Others don't, due to detonation and demands to very high octane gas.

Who's actually running high-compression pistons and do you use the car mainly for track or street?

Michael

Compression ratios are limited by head design and cam timing. While my Hayabusa can run pump gas with 12.5:1 (stock is 11:1 and it runs on 87 octane), a SHO is limited to mid-upper 10s.

I've near ran or rode in a SHO with really high CR, I tend to go the other way .. running 8.5:1 right now...