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What is the max RPM a stock 3800SCII can run? by ILVMYGT
Started on: 07-23-2014 11:25 AM
Replies: 16 (688 views)
Last post by: gtoformula on 07-25-2014 07:15 PM
ILVMYGT
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Report this Post07-23-2014 11:25 AM Click Here to See the Profile for ILVMYGTClick Here to Email ILVMYGTSend a Private Message to ILVMYGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
It looks like the factory setting on the PCM is around 6000 RPM. I have put it on the RPM limiter a couple of times in first gear (5SP). Can the RPM limit be increased safely and how far? As far as I know the motor is stock (internally.)

Thanks
Frank

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88 GT 5 Speed Black with gray interior
3800 SCII Swap.
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BillS
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Report this Post07-23-2014 11:36 AM Click Here to See the Profile for BillSClick Here to Email BillSSend a Private Message to BillSEdit/Delete MessageReply w/QuoteDirect Link to This Post
Why bother? The red line is normally set above power peak, so running it higher would just be useless thrash anyway and might get you into trouble with valve bounce.
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nosrac
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Report this Post07-23-2014 12:06 PM Click Here to See the Profile for nosracSend a Private Message to nosracEdit/Delete MessageReply w/QuoteDirect Link to This Post
Factory is 5300 RPM.
valves will float around 5800 with stock springs.
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nosrac
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Report this Post07-23-2014 12:11 PM Click Here to See the Profile for nosracSend a Private Message to nosracEdit/Delete MessageReply w/QuoteDirect Link to This Post

nosrac

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That was shift points for an auto ^^^

you are hitting the fuel cut threshold which is 5900 rpm.

it can be easily changed but I'd recommend 105# springs.
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dobey
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Report this Post07-23-2014 12:34 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by nosrac:

That was shift points for an auto ^^^

you are hitting the fuel cut threshold which is 5900 rpm.

it can be easily changed but I'd recommend 105# springs.


Springs, lifters, injectors, and pump. Fuel cut is set there for a reason. I'd be worried about the injectors and fuel pump being able to keep up after that point as well, even with the valve float problem solved. No?
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Lou6t4gto
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Report this Post07-23-2014 02:57 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
Don't FIX what isn't Broken. you will gain Nothing and thrash your engine.
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Report this Post07-23-2014 03:50 PM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
Maybe you need more gear?
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Justinbart
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Report this Post07-23-2014 03:59 PM Click Here to See the Profile for JustinbartSend a Private Message to JustinbartEdit/Delete MessageReply w/QuoteDirect Link to This Post
No point in going higher until you get a cam designed for it.

I take mine to 6800-7000 as its magical but It has a big turbo came 150# valve springs balance shaft disabled etc.

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nosrac
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Report this Post07-23-2014 07:07 PM Click Here to See the Profile for nosracSend a Private Message to nosracEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:


Springs, lifters, injectors, and pump. Fuel cut is set there for a reason. I'd be worried about the injectors and fuel pump being able to keep up after that point as well, even with the valve float problem solved. No?


I agree with the Fuel cut safety programming. However, when you are running a CAM, 130+# springs, Turbo, etc. You tend to want to shift at a higher RPM.

However, with a basically stock swap you really don't want to go there as you aren't making any more power just unnecessarily stressing the engine out.
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dobey
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Report this Post07-23-2014 09:36 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by nosrac:


I agree with the Fuel cut safety programming. However, when you are running a CAM, 130+# springs, Turbo, etc. You tend to want to shift at a higher RPM.

However, with a basically stock swap you really don't want to go there as you aren't making any more power just unnecessarily stressing the engine out.


Oh, sure. I think we totally agree that doing it on stock is a bad idea. I was just asking if the stock injectors/pump could provide enough fuel with the cam/springs/lifters/turbo at those higher RPMs. I'd guess one would probably want more spark energy too, depending on how much boost one was trying to run, and what the timing is like.
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ILVMYGT
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Report this Post07-24-2014 03:54 PM Click Here to See the Profile for ILVMYGTClick Here to Email ILVMYGTSend a Private Message to ILVMYGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for all the input.

Frank
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Report this Post07-24-2014 05:47 PM Click Here to See the Profile for BillSClick Here to Email BillSSend a Private Message to BillSEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by nosrac:


when you are running a CAM, 130+# springs, Turbo, etc. You tend to want to shift at a higher RPM. .


Funny, I always had exactly the opposite reaction with my turbo engines. With conventionally tuned NA engines, sure, with higher power making capability at increased rpm you tend to use those rpm more often. With a turbo engine, the torque curve is so fat and level that there is no point running it up high unless you just like the noise and are willing to pay to fix it more often. You just get it up in the sweet spot and then shift and the turbo is pumping all over again in the next gear.

On my 3.2 turbo, I rarely ran it past 5,000 - 5500 because it didn't accelerate any faster if you did, it just makes more noise and stresses things unnecessarily. I did once run it over stock red line in 4th just as a test, but normally no.
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Report this Post07-24-2014 05:57 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by BillS:
On my 3.2 turbo, I rarely ran it past 5,000 - 5500 because it didn't accelerate any faster if you did, it just makes more noise and stresses things unnecessarily. I did once run it over stock red line in 4th just as a test, but normally no.


But that's just because that engine didn't have the right tuning to make power any higher than that. The 3800 can easily be upgraded with cam and valve train to be able to make power at up to 7000 RPM. If your engine can still make power up there, then it's certainly worth it. Revving higher lets you get more use out of the transmission gears too, since you can go more MPH in each gear.
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Report this Post07-25-2014 10:42 AM Click Here to See the Profile for E.FurgalSend a Private Message to E.FurgalEdit/Delete MessageReply w/QuoteDirect Link to This Post
until you upgrade the springs,, and rebuild the lower end with better rod bolts. and polished, full floating small end.. factory rods.. or a good set of aftermarket (does not always = better)
and main studs.. and oil system upgrades.. I'd stick to 5600.
Buick v6's with the right parts can turn 9200 for 500+ laps..
your 3800 needs more than springs to safely be used at that rpm.. and not want to come apart..
not knowing what you have.. I'd guess that your top end and cam would need much work before you'd gain anything past 6000 anyways..
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nosrac
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Report this Post07-25-2014 11:13 AM Click Here to See the Profile for nosracSend a Private Message to nosracEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by E.Furgal:

until you upgrade the springs,, and rebuild the lower end with better rod bolts. and polished, full floating small end.. factory rods.. or a good set of aftermarket (does not always = better)
and main studs.. and oil system upgrades.. I'd stick to 5600.
Buick v6's with the right parts can turn 9200 for 500+ laps..
your 3800 needs more than springs to safely be used at that rpm.. and not want to come apart..
not knowing what you have.. I'd guess that your top end and cam would need much work before you'd gain anything past 6000 anyways..

A stock 3800 SC bottom end is pretty strong. It shouldn't have any issues running up to 6500 rpm. PPL have got into trouble when they try to rebuild it. The conventional wisdom on a 3800 is don't touch the bottom end.
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Report this Post07-25-2014 12:59 PM Click Here to See the Profile for rogergarrisonClick Here to Email rogergarrisonSend a Private Message to rogergarrisonEdit/Delete MessageReply w/QuoteDirect Link to This Post
2 easy steps to determine the max.

1. Go to a used car dealer and find a car with one, take it for a test drive.
2. Find an empty parking lot and hold the steering wheel locked one way and hold the gas to the floor. Note the rpm when it blows up.

Set your rev limiter for a few hundred less than that.

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Report this Post07-25-2014 07:15 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by rogergarrison:

2 easy steps to determine the max.

1. Go to a used car dealer and find a car with one, take it for a test drive.
2. Find an empty parking lot and hold the steering wheel locked one way and hold the gas to the floor. Note the rpm when it blows up.

Set your rev limiter for a few hundred less than that.



Gotta love the simple logic ... and sense of humor.
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