how much extra horsepower from these mods?

[sxyvet]

hi there guys!
how are you all!
just wandering please roughly how much extra horse power i can get up to for my 1991 l98 corvette if i install these corvette hp parts!

i was hoping for 300 horsepwer instead of the standard 260 hp!
here is the list

throttle body air foil/done
k&n air filter with open air box/done
pollution pump pulley ellimanator kit/done
throttle body bye pass coolent mod/done
mat sensor relocate kit
performance switch
hp spark plug leads
bosh plantium spark plugs
high preasure fuel regulator
magnaflow rear free flow mufflers with lt 1 tips and mandrel bent stainlesss exhausts with with i single high flow cat/done
hi performance pulley kit
hyper tech power coil /cap kit
hei control module
adjustable throttle position sensor
power coupler/ intake hose straight design with out crinkles/ribbed.
power aid throttle body spacer
also have tried 160 degree thermostat, does this really help with performace?

are these mods a good start?

i am on a bit of a budget so i thought this would be ok!


was told that bye bye corvette central that bye removing vaccum hose of fuel regulator and manifold on other end that you can gain 5 lb of fuel preasure which i tried with my fuel preasure guage and it boosted it up to 45 lb!
what i did was add a mower fuel small filter on each end so that it doesnt suck up dirt or any thing!
is this safe to do like this?
does bye disconnecting it really work?

any other mods/tips info would be really appreciated very much!
thanks heaps
glen
sxyvet-australia
sxy_corvette@hotmail.com

 

[nyernga]

hi there guys!
how are you all!
just wandering please roughly how much extra horse power i can get up to for my 1991 l98 corvette if i install these corvette hp parts!

i was hoping for 300 horsepwer instead of the standard 260 hp!
here is the list

throttle body air foil/done
k&n air filter with open air box/done
pollution pump pulley ellimanator kit/done
throttle body bye pass coolent mod/done

hp spark plug leads
bosh plantium spark plugs
high preasure fuel regulator
magnaflow rear free flow mufflers with lt 1 tips and mandrel bent stainlesss exhausts with with i single high flow cat/done

hyper tech power coil /cap kit
hei control module


are these mods a good start?

i am on a bit of a budget so i thought this would be ok!


was told that bye bye corvette central that bye removing vaccum hose of fuel regulator and manifold on other end that you can gain 5 lb of fuel preasure which i tried with my fuel preasure guage and it boosted it up to 45 lb!
what i did was add a mower fuel small filter on each end so that it doesnt suck up dirt or any thing!
is this safe to do like this?
does bye disconnecting it really work?

any other mods/tips info would be really appreciated very much!
thanks heaps
glen
sxyvet-australia
sxy_corvette@hotmail.com

Leave off the ones I deleted and use the money towards a set of headers. Of what you've done so far, the biggest boost comes from the exhaust. DO NOT use the air tube that's smooth. It doesn't handle the engine compartment heat well and will split down the center. That'll leave you with a code 34 ........MAF sensor
I installed a high performance chip about 4 years ago minus the 160 degree t'stat and I noticed a slight increase in torque but that was about it.

Len

 

[Hrtbeat1]

Leave off the ones I deleted and use the money towards a set of headers. Of what you've done so far, the biggest boost comes from the exhaust. DO NOT use the air tube that's smooth. It doesn't handle the engine compartment heat well and will split down the center. That'll leave you with a code 34 ........MAF sensor
I installed a high performance chip about 4 years ago minus the 160 degree t'stat and I noticed a slight increase in torque but that was about it.

Len

The '91 is a SD car .... ie no MAF so I don't think it would get the code 34. Other than that I agree. Headers make all the difference in these cars. Very noticeable boost in HP.

sxyvet

One thing you can do is go with a K&N cone filter right on the end of the TB. '90 and '91 are the only ones that can do this due to not having a MAF. I did it on my '90 and swear I could tell a difference. I've heard that they actually reduce HP due to the air being drawn in is more heated from the engine. I had planned on doing dyno tests to verify or debunk this but never got the chance.

 

[nyernga]

Len

Not being nitpicky but the '91 is a SD car .... ie no MAF so I don't think it would get the code 34. Other than that I agree. Headers make all the difference in these cars. Very noticeable boost in HP.

 

[vetteboy86]

Actually a set of TPIS long tube headers with good cat back would be the biggest bang for you buck mod. All those things are okay to do, but I dont think you will be happy. I have been in the same boat as you are now.

I am confused about what you are doing with your fuel pressure regulator. Yes by removing the vacuum line you will see more pressure on your guage.

 

[sxyvet]

thanks guys for your info and replys!
so the other mods wont help much?
can i get 300 hp out the engine with all those mods?
how much are the headers or extractors any way?
thanks glen
sxyvet-australia

 

[nyernga]

I'm not an expert but headers, muffler upgrade and the K&N open air filter would probably free up anywhere from 15 to 25 extra hp. Helping the engine "breathe in and out" is the best mod you can do for the money.
Just shy of buying a ZR-1 I'd say you're on the right track....

Len

 

[Edmond]

Mad Mic said that TPIS headers are good for 20 HP and I can see why because the stock manifolds are absolutely horrible.

One thing about the stock L98 exhaust system is that it only flowed through one outlet per muffler. With the aftermarket systems, both outlets flowed. The stock L98 exhaust is a very restricting exhaust system.

You would see quite a nice gain, at least 30 HP is you did the whole exhaust from headers, through high flow cat to the aftermarket mufflers. Plus, you'll get a nice improvement in the sound of the car. It will really roar.

TPIS headers aren't cheap, about $750 last time I checked.

A nice tuneup should also be done. It won't increase power, but it will restore lost power.

 

[vetteboy86]

I think headers is an easy 20 rwhp mod. Remember that is probably anywhere from 35 to 40 hp at the fly wheel on these cars. The stock manifolds suck,and the exhaust is so restrictive.

If you did some intake mods with the exhaust you wouldn't have to worry about the small mods now, and so them as needed. So for instance you you got a cold air induction system, like the ram air, ported plenum, port match the gaskets on the runners, an air foil in the throttle body, you would be sitting pretty. The car would be feel alot different for you. I know that just going to the raim air setup, it made a huge difference once you were at speeds past 40 which is where we need it the most. Porting the plenum is very easy.

 

[sxyvet]

I think headers is an easy 20 rwhp mod. Remember that is probably anywhere from 35 to 40 hp at the fly wheel on these cars. The stock manifolds suck,and the exhaust is so restrictive.

If you did some intake mods with the exhaust you wouldn't have to worry about the small mods now, and so them as needed. So for instance you you got a cold air induction system, like the ram air, ported plenum, port match the gaskets on the runners, an air foil in the throttle body, you would be sitting pretty. The car would be feel alot different for you. I know that just going to the raim air setup, it made a huge difference once you were at speeds past 40 which is where we need it the most. Porting the plenum is very easy.

thanks for that info!
are headers better or extractors better?
which brand is better also?
with extractors is 4 into 2 better than 4 into 1 pipes?
my 1991 corvtte is converted to right hand drive so does that mean when i buy for exapmle the headers or extractors that on one side may hit on something due to the fact the extractors are made for left hand drive cars and not right hand drive cars?
thanks
glen
sxyvet-australia

 

[Vettelt193]

thanks for that info!
are headers better or extractors better?
which brand is better also?
with extractors is 4 into 2 better than 4 into 1 pipes?
my 1991 corvtte is converted to right hand drive so does that mean when i buy for exapmle the headers or extractors that on one side may hit on something due to the fact the extractors are made for left hand drive cars and not right hand drive cars?
thanks
glen
sxyvet-australia

do you have pictures of your car? The drive train is off center on C4's... did they move everything over, or do you have a smaller area to drive with?

Please post pics if you can, I know I am really interested in seeing your car converted, and others will be too.

 

[vetteboy86]

thanks for that info!
are headers better or extractors better?
which brand is better also?
with extractors is 4 into 2 better than 4 into 1 pipes?
my 1991 corvtte is converted to right hand drive so does that mean when i buy for exapmle the headers or extractors that on one side may hit on something due to the fact the extractors are made for left hand drive cars and not right hand drive cars?
thanks
glen
sxyvet-australia

Not sure what you mean by extractors? I have always heard reference to headers. As far as your question about 4 into 2 bieng better then 4 into 1, that is something you would have to research. What you want to look at is the scavenge effect from each. This is essentially the potential from the previous cycle to help pull the next out of the combustion chamber. I guess you can think of it like vacuum.

I am having a hard time thinking about how a C4 is converted to right hand drive, but I bet you will have to call some header companies and ask them about this.

Good Luck

 

[vader86]

throttle body air foil/done-CRAP
k&n air filter with open air box/done
pollution pump pulley ellimanator kit/done-No power gains at all
throttle body bye pass coolent mod/done-small gain
mat sensor relocate kit-Useless
performance switch-more useless
hp spark plug leads-cutback the plug electrodes
bosh plantium spark plugs-fine, but you can get the same performance from Rapidfires for less money
high preasure fuel regulator-always a good idea
magnaflow rear free flow mufflers with lt 1 tips and mandrel bent stainless exhausts with with i single high flow cat/done=about 10-12hp
hi performance pulley kit-I dont like them, but they could give up to 10hp
hyper tech power coil /cap kit-useless, get the stock Delco part
hei control module-useless on a motor with these mods
adjustable throttle position sensor-fine
power coupler/ intake hose straight design with out crinkles/ribbed=no power gain
power aid throttle body spacer-complete crap
also have tried 160 degree thermostat, does this really help with performace?=yes and no http://temp.corvetteforum.net/c4/vader86/160.html

Pay close attention to what I've written here.
You want power, spend some money. You should start next with Hooker or TPiS longtube headers, then consider AS&M runners and a BigMouth Base.

 

[vetteboy86]

There are some mods that you listed that are fine, and would equate to good quality time with your car. Not to mention anything you do is a learning experience.

 

[Vis Croceus]

I think headers is an easy 20 rwhp mod. Remember that is probably anywhere from 35 to 40 hp at the fly wheel on these cars.

50% drivetrain loss!

 

[sxyvet]

do you have pictures of your car? The drive train is off center on C4's... did they move everything over, or do you have a smaller area to drive with?

Please post pics if you can, I know I am really interested in seeing your car converted, and others will be too.

g,day there!
thanks for the reply!
when converted to right hand drive as all cars in australia legally have to be converted to right hand drive apart from cars that are 20 years or older now as they are classed as classics!
every thing was converted over properly!
infact it looks like factory job done!
it takes about 4 weeks to complete!
and $20,000 aus dollars to do!
i would love to post up pictures for you guys one day but dont have scanner at the moment!
thanks
from glen
sxyvet-australia!

 

[tntcorvette]

hi there guys!
how are you all!
just wandering please roughly how much extra horse power i can get up to for my 1991 l98 corvette if i install these corvette hp parts!

i was hoping for 300 horsepwer instead of the standard 260 hp!
here is the list

throttle body air foil/done
k&n air filter with open air box/done
pollution pump pulley ellimanator kit/done
throttle body bye pass coolent mod/done
mat sensor relocate kit
performance switch
hp spark plug leads
bosh plantium spark plugs
high preasure fuel regulator
magnaflow rear free flow mufflers with lt 1 tips and mandrel bent stainlesss exhausts with with i single high flow cat/done
hi performance pulley kit
hyper tech power coil /cap kit
hei control module
adjustable throttle position sensor
power coupler/ intake hose straight design with out crinkles/ribbed.
power aid throttle body spacer
also have tried 160 degree thermostat, does this really help with performace?

are these mods a good start?

i am on a bit of a budget so i thought this would be ok!


was told that bye bye corvette central that bye removing vaccum hose of fuel regulator and manifold on other end that you can gain 5 lb of fuel preasure which i tried with my fuel preasure guage and it boosted it up to 45 lb!
what i did was add a mower fuel small filter on each end so that it doesnt suck up dirt or any thing!
is this safe to do like this?
does bye disconnecting it really work?

any other mods/tips info would be really appreciated very much!
thanks heaps
glen
sxyvet-australia
sxy_corvette@hotmail.com

You will not get 40 hp with all that stuff on your car.

I'de keep what you got, and get:
ASM Underdrive crank pully
MAT sensor relocate kit
Hypertech or equilavent chip
Adj fuel pressure regualtor (no need to go crazy with the fuel pressure. Just minor tweaking)
180 state
Basic tune up with quality parts
Hooker 2149 headers (2151 do not have emission hook up)
Cat back of your choice. Magnaflow is fine

I think the above mods will get you a solid 20 hp gain.

Then we need to either dig in the motor for more hp or the intake.

For starters in the motor you can get new valve springs and a set of 1.6 rocker arms. I'de bet on ~10 hp with the rocker arms.

For the intake i'de personally leave the stock TPI on there for now until you can do a total all at once upgrade on the intake from the manifold to the throttle body.

 

[sxyvet]

You will not get 40 hp with all that stuff on your car.

I'de keep what you got, and get:
ASM Underdrive crank pully
MAT sensor relocate kit
Hypertech or equilavent chip
Adj fuel pressure regualtor (no need to go crazy with the fuel pressure. Just minor tweaking)
180 state
Basic tune up with quality parts
Hooker 2149 headers (2151 do not have emission hook up)
Cat back of your choice. Magnaflow is fine

I think the above mods will get you a solid 20 hp gain.

Then we need to either dig in the motor for more hp or the intake.

For starters in the motor you can get new valve springs and a set of 1.6 rocker arms. I'de bet on ~10 hp with the rocker arms.

For the intake i'de personally leave the stock TPI on there for now until you can do a total all at once upgrade on the intake from the manifold to the throttle body.

hi there tnt,
thanks for the info!
where can i buy hooker headers from?
how much?
thanks
glen
australia

 

[Edmond]

hi there tnt,
thanks for the info!
where can i buy hooker headers from?
how much?
thanks
glen
australia

www.jegs.com

or

www.summitracing.com

I believe they're in the $500 neighborhood but I don't know if they come with the front y-pipe or not.

I know the TPIS header system comes with the y-pipe for about $750 from:

www.tpis.com

TPIS is reputed to be one of, if not the best, header system for the C4.

 

[tntcorvette]

www.jegs.com

or

www.summitracing.com

I believe they're in the $500 neighborhood but I don't know if they come with the front y-pipe or not.

I know the TPIS header system comes with the y-pipe for about $750 from:

www.tpis.com

TPIS is reputed to be one of, if not the best, header system for the C4.

Check out the TPIS system too as from what I recall Hooker had a tooling problem with their front y-pipe making it fit correctly but that was years ago so hopefully they have fixed it.