C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

rpm limits?

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Old Feb 5, 2008 | 10:40 PM
  #1  
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From: berwick pennsylvania
Default rpm limits?

just read the "another 11 second vette thread" in this tread neat talks aboubt reving above 4800 with a stock tpi intake setup. what i would like to know is could anyone give me a ballpark figure on my rpm limits with my current setup.my cam is supose to make power to 55-5600rpm, will my intake get me there?

my intake set up.

breathless performance ram air
holley 58mm throttle body
exotic muscle fully ported plenum
exotic muscle extruded lrg tube runners
tpis big mouth intake fully ported and gasket matched for a 1205 gasket
pro topline 195cc aluminum lightning heads mildly worked
all sit on top a nice stout 383ci stroked l98
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Old Feb 6, 2008 | 03:06 AM
  #2  
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I have almost identical setup except for siamized stock base.

383, 195TFS, 58mm 226/ .560 cam.
I am fully aware of the TPI limitations , used to get best track times on 350 shifting at 4500 rpm ( same intake setup ) but the Datamaster logs are showing me pulling over 6K.
Have fuel cutoff set to 6400 and have hit that several times.
Have yet to run on dyno to see actual Hp curve

If you look at the various TPI setups in this comparison (288HR cam )
all except the AS&M peak below 5K but run out to 6K without a noticible drop off.

http://www.compcams.com/Community/Ar...?ID=1737510521
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Old Feb 6, 2008 | 08:19 AM
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havent hit the dyno yet. have some tranny issues to iron out first butthere is one in towm that i would like to hit
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Old Feb 6, 2008 | 08:27 AM
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I have reved my stock motor to 5300 before. Wasnt making pwr, but it went there!
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Old Feb 6, 2008 | 09:30 AM
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me to. it was like takin a whiz into the wind though. got the job done but only askin for trouble
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Old Feb 6, 2008 | 10:05 AM
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Originally Posted by 85blkrose
me to. it was like takin a whiz into the wind though. got the job done but only askin for trouble
i dont want pics.
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Old Feb 6, 2008 | 10:31 AM
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With the original TPI setup mine would rev to 5500+ but you had to wait all day to get there.Thats with a polished/ported TPI plenum,Accel runners,Accel ported/polished base,big valve ported D heads,219 cam and all the rest.It would trap at 5000 in third and just plain out of steam.Putting the superam on there has made a fantastic difference.Not run it at the track yet but it pulls smoothly all the way to 6200 so I expect to see my times come down a lot.Here's Lingenfelters graph for the motor.

Last edited by staugur; Feb 6, 2008 at 10:36 AM.
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Old Feb 6, 2008 | 03:18 PM
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You should be able to hit 6K RPMs if you have the proper aftermaket cam, valves, valve springs, etc. since attaining a high RPM's is mostly a function of your valvetrain.....

Now.....attaining those high RPMs and making power is much more a function of the intake and heads......and the stock intake will severly limit power at those RPMs.

KW
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Old Feb 6, 2008 | 09:39 PM
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Originally Posted by staugur
With the original TPI setup mine would rev to 5500+ but you had to wait all day to get there.Thats with a polished/ported TPI plenum,Accel runners,Accel ported/polished base,big valve ported D heads,219 cam and all the rest.It would trap at 5000 in third and just plain out of steam.Putting the superam on there has made a fantastic difference.Not run it at the track yet but it pulls smoothly all the way to 6200 so I expect to see my times come down a lot.Here's Lingenfelters graph for the motor.
That LPE example should shift by 5250RPM to get the best power. You will hear lots of people claim that there LT TPI set-up makes power well past the 46-4700 that it should be shifted, but they have no "real" data to back it up (SOTP data doesn't count).

On one of my earlier combos with large tube runners, larger base, and heavily ported plenum, peak TQ was at ~4400, while peak HP was at ~5050. This combo should have been shifted right at 5000RPM. The change to a SR only pushed the peak HP up to just over 5400. MRII was higher yet at 5850RPM.

Even with a C4SP, peak TQ was just shy of 5600, while peak HP appeared to be at ~6100, though there was no drop through 6200 (where the dyno pulls stopped). This car has the shift light at 6000RPM, but shifts usually occur at 6150 (reaction delay). Shift after peak TQ and right at peak HP. The next gear should place the engine close to the peak TQ value.

Aaron
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