ok.....1991 Z28 5.7 L98 TPI.......Ram Air Boxes, K&N Air Filters,
52 MM BBK/Edelbrock Throttle Body, TB bypass, MSD-6A Ignition, 3 inch catback Flowmaster 80 series exhaust, both cats removed, 3 inch exhaust cut with 3 inch McCord Power Plate II, and 3 1/2 tips...stock...the 1990-1992 Z28 L98's came with 245 h.p. and 345 lbs of torque.......any guesses? Or...guesses on what my time might be in the 1/4 mile? Any thoughts/suggestions would be great too....thanks fellas

 

I'll guess 265 hp
should be good for high 13's in good air.

 

About the same as a stock L98. Those Mods are not going to change the stock numbers by much. In fact you may have lost power with some of your changes.

 

IMHO He didnt loose any power but he for sure isn't in the 13s. On what basis do you think he lost power? The 52mm tb? My recommendation is to look into an aftermarket roller cam and headers as your next purchase.

 

Loss of power...?? I really don't think that's going to happen....the exhaust it self has provide atleast 10-15 h.p......and the ram air boxes....there is 5-10 right there. So..I really don't think there will be any loss of power. Yeah....my next step is to get a nice set of coated headers when I get the money. I mean..I'm not trying to make a race car.....just a quicker then stock street car. But....keep the comments and opinions coming....oh yeah...I agree I'm also not going to hit 13's....no biggy to me....

 

Why not just not buy the MSD and the throttle body, then you would have enough for headers

 

Because they are already bought.....

 

Just remenber you don't make Horsepower by adding up all the Mods you make on your car.
Exhaust= 10/15
Ram air = 5/10
Does not mean you added 25 HP to your stock engine.

 

52mm throttle body = a waste of 300+ $ that would be better spent in other areas.

like headers or a cam or a torque converter. think about porting your intake too... you will see more from do that than a TB anyways, and it doest cost 300 beans either.

 

I bought the BBK/Edelbrock TB for only 175 dollars....already has an aftermarket torque converter and shift kit (guy had a new $1500.00 tranny installed before I bought it not sure what kind though). Couple guys I know have bought the TB and said they got a quicker throttle response (not much extra hp or anything)....thats why I bought it....plus..it was a great deal....but yeah Z28DJP1987....I know what your saying about adding up things like that....but....how would there be a loss of any power? Those aftermarket parts will have to do a lil more then stock parts.....they didn't make these aftermarket parts to make your car lose power....they will have to gain a lilttle.....and again..I'm not wanting to make a race car here.....just a little quicker then a normal 90-92 L98 Z28 street car...

 

Yes you replaced some stock parts with better replacements, but not enough to make a big difference. The loss of power remark was about the oversized thottle body on the almost stock engine.
so good luck on your project.

 

I would say about 265-270 HP which is good for pretty low 14s.

So many people on here are quick to ridicule a larger TB when in reality they have ZERO experience with it and are basing their opinions from what they've read (For those that DO have experience with larger TBs then I'm not talking to you). If your friends saw in improvement with adding it then I would listen to them.

A decent set of headers *should* land you in to the high 13s pretty easily.

 

Thanks for all of the replies guys....a set of headers should do the trick...before I bought the TB....I did some research to make sure I wasn't making a mistake....like if ithe 52MM TB would detune the engine or something. The 52MM TB is used for engines that haven't been modded much....they gave an example of an aftermarket full exhaust system....like I'm running....now..they also make a 58MM TB (most of you guys know)....but..that's used for engines that are more radical...and is unable to be used without having the plenum ported and such. But I'm taking everyones opinions/comments in consideration and I really appreciate it. I won't be installing any of these parts until spring/summer...so..it's going to be awhile...I just thought you guys might have some good ideas....on what to expect...

 

Might as well install the TB if you already have it....it takes like half an hour tops

 

Headers will wake it up.

The MSD won't give you any gains. Maybe quicker starting and a tad increase in gas mpg.

The Ram air boxes are worth 5-10 HP at WOT.

And before people start flaming, I've seen ACTUAL DRAGSTRIP TIMES from JUST ram air boxes on a TPI car. Okay not ram air boxes, but 4" piping run from the fog light opening to the filter area w/ cutouts in the lower air box. Hell it's worth it for the extra "scream" at WOT

Almost a FULL 2 tenths reduction in ET, and the ET was consisent enuff before the install he ran within 1 tenth pretty much all year. Guess that's why he always dominated the foot brake class in brackets :P

TO be honest, gains might be a tad less on yours, since you still need to address the exhaust ( headers ).

The bigger throttle body is a toss up on a "stock" engine. And to be honest, you really need to burn a chip to compensate.

Next logical step ( after headers ) is a good set of heads....good heads will run better w/ the stock cam than stock heads w / a good cam ANYDAY.


HTH

 

Hey 84customz28 nice work the car looks great (sig).

I can't agree with the 13s talk I know guys running similar setups if not better (275hp/390lbs torque), who are struggling through 14s even though on paper their cars are sub14 second.

You haven't addressed the transmission (even thouigh somebody before you did 'something') and you have not addressed traction. So what if you make 350+ lbs torque you have to put it to the pavement.

So if you are absolutely certain you were making factory numbers (245/345) before the mods then it is reasonable to assume you collected another 10-15hp and 7-10 lbs torque IMHO mostly due to exhaust work.

My guess/estimate is a 14.4x ET at 95mph.

Pay for some dyno pulls and get some rwhp numbers -- atleast you'll know where your power curve is. ALSO expect to be surprised we always make less power than we ever dreamed of...
Then go to the track, do a few runs and post your numbers.

adious,
RP.

 

I like the experiance comment... 1/4 mile time is doesn't really matter ( woops did I say that ) unless that is where you plan on spending a lot of your time. It's the torque thing. Street power is a diffrent world. To install a cam shaft isn't nessarrily the best mod to make. I replaced my cam shaft along with the lower end, put in a 5.7 inplace of the 5.0 and it wasn't any better than it was with a 5.0. Just the headers is where a good diffrence can develope. The real modifications come when you start improving efficiency. The ability to move air/fuel. that is why that throttle body is a good choice. It will help some now but in the future it will help a great deal. Installing a small aftermarket cam in my opinion's a waiste of time and money with out the heads, manifold, plentum, runner work and the headers to make it perform correctly. The second time I did this...


* Ported & Polished Cylinder Heads 993 castings
* 2.02 & 1.6 Manley Pro-Flo Valves
* G.M.P.P. Ram Jet Roller Cam Part # 14097395 - already had..
* Harland Sharp 1.6 Ratio Roller Rockers
* Speed Pro/TRW 1.25 Dome Forged Pistons
* Balanced Lower End
* Ported and Gasket Matched Intake Plentum, Runners and Manifold
* 52MM Holley Throttle Body
* Custom built Adjustable Fuel Pressure Regulator Set at 46 lbs ( 51 under Full Throttle )
* OEM #19 injectors ( working perfectly with combination )
* Edlebrock Chrome T.E.S. Headers -- 50 State legal --
* High-Flow 3" Carsound Cat with 3" Flowmaster Cat Back System

The Prom, detination sensor, Injectors and what ever else is all OEM. It all works perfectly. I've had a couple of 12 second carb'd cars in the last 30 years and never have I had a car so quick out to find it's horsepower. It's the torque... Now I'm positive the 68 Camaro I had would run this thing down or maybe run off and leave it in the standing 1/4 mile. On the street I just don't know... it would probley never catch it, from a roll, considering the top speed of the Firebird and how quick it gets there. I doubt it...

I ran off a couple of car links on a LT1 Camaro lastnight and he got a little jump on me. First time with this combination. 70 to 120 in a few seconds.. man was I shaking afterwards..LOL

 

The only reason I base it on tracks results is because a track is the closest thing to a controlled environment and you have actual times to compare. Instead of "I used to be even with my buddies 'Stang, then I added headers and now I smoke him" (LOL, you get the idea.)

I am more concerned about what I run on the street though which is why I refuse to use drag radials at the track. I leave my tires at the stock pressure too (275/35-18s at 40psi).

90Formula-X-F: What part of Sac are you in?

 

I live off Truxel, Work out in Roseville. How about you ?

 

Rancho Cordova (Sunrise & U.S. 50). There's about 5 or 6 of us in this area alone (Sac County)

 

Kewl , Sometime when eveyones taking the cars out, I'd like to tag along...