How much horsepower?

[Alfonso Gomez]

OK, this is a tough one: my 1987 Coupe(Automatic transmission) has the following mods:
KN filter
Cut-out filter cover
160 degree thermostat
Bypassed throttle body coolant
Throttle body air foil
Thermomaster chip by Hypertech

I guess this should give me an extra 10-15 horsepower. Correct?

Next will be:

Front Y-pipe 2.25" without small cats
Rear Y-pipe 2.25" with heat shields and crossover pipe (for reducing resonance)
Dynomax or KBD Targa mufflers (no eliminator pipes: probably too loud). These mufflers should reduce back pressure.

How much extra horsepower should I expect? I don't want to open the engine for mods since this is a daily driver. Plus, my wife would kill me.

Are bigger runner tubes advisable or will it require a bigger throttle body?:Twist

 

[Vettelt193]

sounds about right...

The exhaust should add another 5-10, figure a total of 15-20 hp total.

The TB will add power, so will the runners... I would suggest doing them both (wait until you can get it all done if you don't want to spend the money now)... This will really help your L98 breath, but it will also increase your peak HP RPM, so you will get more power on top

 

[Eagle85C4]

I recently replaced the whole exhaust system on my 85 for a 1000.00.... I put 2 1/2 inch stainless front to rear with Borla stainless mufflers with dual 3 inch outlets. At first it was a bit loud and had some resonance...but after a few miles it has gotten a lot quieter. Now I get nothing but compliments on how it sounds...especially at WOT. Performance wise it did take a bit of the bottom end torque away but moved it up into the mid range which is alright by me. It is nice knowing I will never have to replace it again.

 

[CorvetteArchives]

I agree with Eagle.........never regretted adding the Borla exhaust.....sounds great, lasts forever, and adds performance. Win WIN WIN

 

[Vrotate]

Mods

Have the exact same mods on my 87 4+3. Noticed a big difference in my car. Just put KBD 3" mufflers on, sound create, no resonence. (Have rear Y pipe though)

 

[tntcorvette]

now that I think about it, I purchased a 2.5" front y pipe about 4 years ago. If I could do it again, i'de just get a set of headers.

If you dont mind, the hookder 2149 have emission hook up & 2151 do not. You may want to not get them coated because the coating is not that great. Im going to send mine to get jet hot coated after 2 years of use.

These headers have a matching front y pipe and you can use your cat and what ever cat back you want.

 

[maxrevs85]

Headers

Be sure to check out TPIS. They have a coated header and have all the required hookups for emissions . They were the easest header I've ever installed. Just raise the car and slide them in. And they come with the big Y-pipe made for your car with clamps. I rate them excellant!!

 

[johnny]

hp en torque

The little mod help a bit to increase your performance, but if you really want too feel a big difference, you should add some other mods.

You should use the LPE/Accel SuperRam and a set of Edelbrock performer heads.

Last week, I run 172 MPH in 5th!

 

[johnny]

 

[Edmond]

Johnny,

Is that unit the same as the TPIS one?

You have to get the unit for $900 and then new fuel rails for about $500 right?

That's quite a bit of money. But I've read that the ram system can add up to 95 horses with other modifications.

 

[-=Jeff=-]

Johnny,

Is that unit the same as the TPIS one?

You have to get the unit for $900 and then new fuel rails for about $500 right?

That's quite a bit of money. But I've read that the ram system can add up to 95 horses with other modifications.

NO, Johnny has the Super Ram Made by Accel Designed by John Lingenfelter..

I have a Miniram.. Made By TPiS

 

[johnny]

Correct!

But I use the 1000 cfm TB form Holly, the new one. It is a bit at the LARGE size, but I want in the future a Whipple Charger. So I decide too try this one out.

In my setup, it made about 28 hp and some higher topend speed.

And a lot of fuell!!!

So as you also can see, I have a homemade airfilter and when you have a closer look, your see my sequential injection system. With two inigtioncoils.

I am not sure, but the LPE SuperRam with the runnera and baseplate should flow about 1280 cfm, very usefull to combine with a Vortec superscharger.

BUT!

The big difference between, the stock setup and the LPE/Edelbrock setup is, higher RMP's! My vette runs 6250 RMP and when I hit the throttle at 4000 RMP jou will be lauched! You never raced your vette so fast before.

Try it, you will like it, esspecial when you drive a zf6.

 

[Edmond]

So what those units do is allow the vehicle to run at higher RPM's right?

 

[johnny]

Yes the hp and torque curve is totally different. You should try a LT4 with 6 speed, I think you have the same kick.

 

[BigRed]

My future build is based around the TPiS Mini Ram. Actually Ive heard mixed reviews but I know Jeff and 69myWay run one. How noticable was the gain?

Mabe I can list a few of the mods planned and you guys can tell me what to expect.

TPiS Mini Ram w/ the Fuel rail of course
24# Injectors
54mm TB W/ Foil
TPiS Headers
3:73 Gears using original Carrier
DynoMax Mufflers (1200 CFM each)
Y Pipe ---> No cats (Using Cheaters)
K&N w/ Cut Air lid
89 Computer W a Jeff Custom PROM :t
Complete MSD Ignition w/ Bosch +4's

Do I have to change the heads? Is the Gain that much more? I was trying not to pull the motor but if a head change is in order then I'll just rebuild the engine using some internal Mod parts.

 

[johnny]

My future build is based around the TPiS Mini Ram. Actually Ive heard mixed reviews but I know Jeff and 69myWay run one. How noticable was the gain?

Mabe I can list a few of the mods planned and you guys can tell me what to expect.

TPiS Mini Ram w/ the Fuel rail of course
24# Injectors
54mm TB W/ Foil
TPiS Headers
3:73 Gears using original Carrier
DynoMax Mufflers (1200 CFM each)
Y Pipe ---> No cats (Using Cheaters)
K&N w/ Cut Air lid
89 Computer W a Jeff Custom PROM :t
Complete MSD Ignition w/ Bosch +4's

Do I have to change the heads? Is the Gain that much more? I was trying not to pull the motor but if a head change is in order then I'll just rebuild the engine using some internal Mod parts.

Yes I think you should use better heads, the gain is bigger. And forget the TB 54mm. Lot of people use to big TB's, the stock TB will do fine (if not better). Why bigger injectors? Use the stock injectors with a adjustible fuell pressure switch. The TPIS mini ram is okay. If I would live in the US, I would buy the AFR heads. The headers 1 5/8 " will do fine, the 1 3/4" are for bigger engines.

 

[-=Jeff=-]

My future build is based around the TPiS Mini Ram. Actually Ive heard mixed reviews but I know Jeff and 69myWay run one. How noticable was the gain?

Mabe I can list a few of the mods planned and you guys can tell me what to expect.

TPiS Mini Ram w/ the Fuel rail of course
24# Injectors
54mm TB W/ Foil
TPiS Headers
3:73 Gears using original Carrier
DynoMax Mufflers (1200 CFM each)
Y Pipe ---> No cats (Using Cheaters)
K&N w/ Cut Air lid
89 Computer W a Jeff Custom PROM :t
Complete MSD Ignition w/ Bosch +4's

Do I have to change the heads? Is the Gain that much more? I was trying not to pull the motor but if a head change is in order then I'll just rebuild the engine using some internal Mod parts.

Are you using the stock cam? with the iron heads?

I would swap cam and atleast go to Aluminum heads. While everybody says AFRs, I would suggest Brodix or Canfield..

The miniram is not designed for the Stock cam and heads..

As for the TB I agree with Johnny.. the 54mm will be too big especially since you are keeping stock displacement. I have a 52mm TB on mine right now, but have a 58 on the shelf I want to compare with at some point. The 48 should work okay though

1-5/8" headers Not many companies make that size for our cars.. the 1-3/4" will work fine.

24# injectors are stock in a 1985 vette so I would have yours cleaned (depending on mileage) I actually am using 30# SVO injectors on my set-up and by doing so I can keep the duty cycle lower at WOT.

I also would not bother with the Bosch +4s I use stock OEM AC Delco plugs.. You could get the AC Rapidfires but that would be all.


In order for that Miniram to run at its full potential the heads and cam will help.. if you stay stock they will be your choking point

 

[BigRed]

Ok you got me..

I was in the end going to go with a 383 Stroker or a Crate one. That said I would like to get my exhaust and intake ready for it Via 54mm TB's and bigger injectors. (What # do you suggest?)

Before the stroking Im going to install either EdelBrock or TPiS's heads. CompuCam/Roller Cam from Crane or TPiS's answer (Im not a cam literate guy)

Ive got the Stock TB of course but after that setup is a 54mm TB warranted? Will that 54mm hurt me that bad?

so with a stock bottom end a "different" cam and Edelbrock or TPiS heads (And all the other listed stuff) how would I add up you think?

(Leave my +4's alone! I love em hehehe :J )

Jeff the reason why all the planning is Im building my house in 2 years and Im currently going to auctions for stuff and building it myself. When I go for a loan on the house Im going to have some extra play doh to deal with. Im thinking in the 7500-10K mark. I would like to add it to the car. However many people are telling me to sell the 85 and upgrade. (After all the work I have into already Im not a willing candiate for that)

My brakes will be upgraded, I'll be redoing the interior, and putting on Y2K wheels. so...basicly a new car.

I just want to hit the 12's possibly the 11's at around the 400-500Hp mark (Flywheel)

 

[69MyWay]

I would guess you are very realistic about true useable hp after those small bolt on mods. They do help give you a snappier throttle response and that alone makes the car feel faster.

These other mods mentioned are extreme. However, if you want your L98 to run with the least of the LT1 generations, you will have to really step up and replace the intake manifold with one that will do the job.

I prefer the miniram, but that is all I have experience with. I have heard good about the LPE Super Ram, etc.

You can get a long way with a larger bottom intake (or port yours out), larger runners, ported upper intake (smoothed) and 52 mm TB. That will help move the power band up a tad giving you more useable hp.

 

[johnny]

I have some dynoruns, it is in km/h and Nm, but you can convert them!

http://users.iafrica.com/l/ld/ldarby/torquevert.htm

Mesurements are ALWAYS different, day by day! Today you have 200 hp and tomorrow 205HP, difference you will see in the type of Dynobench. I only tested my car on the ones with ONE roll, so there is no difference in the type of tires or how you handle the throttle.

This one you see a stock 86 vette with a 91 engine, a borla exhaust and the stock aluminium heads. (this heads they made late 86)

you see the max torque at 3300 rmp and the max hp at 4400 rmp