Last time I went to the track I could only run a 15.5 @ 94mph. I know I may be losing traction but I still think that since I have an l98 with full exhaust I should be running slightly faster. Shouldn't a bone stock 350 be a mid 14 second car? Also Iroc-Z's and Z28's at my track don't see 14's and LS1's with mods don't hit 12's too often...could it be the track? I just put on 3.43's, posi, subframe connectors, and an adjustable panhard bar and should be running 14's...but it seems like I have to do soooo much to this car to get it fast. I was wondering if my ultimate TBI is now holding me back. It seems like after 4000 RPM I don't pull anymore. Anyone with an idea would be helpful.

 

Whats the elevation at the track you are running at? The higher you go the slower you become. Temp, bar pressure and humidity( altitude density )also play a large part of the equation.

Steve

 

There's your biggest problems right there. j/k

What cam and heads do you have? The stock L98 TPI stuff? What year engine is it? What do you have your initial distributor timing set to?

A bone stock L98 TPI is a mid 14 second car, but with TBI on it, its a different story.

 

You sure it's a L98? That sounds about like a L03 with some good mods.

94 mph for 15.5 tells me also that you have no traction, 94 should be 14.8 or so. What was your 60ft? I would check your base timing like they said above, advance it to 6-8 degrees.

Could be the elevation to.

 

Well, I am almost 100% sure it is an L98. My L03 had a blown head gasket on it...and decided to swap up when I did the change. Yes, it still has stock heads and cam. My track elevation is basically sea level...I think around 400ft. My 60ft times were horrible...I ran a 2.6 60' but that was on a cold winter day so my power will probably drop slightly too...was about 40 outside. But when I did hook...well 2.3 I still only ran a 15.3. But that's not my question...I know if I had a TPI with full exhaust some intake work I would probably be in the high 13 low 14 range...am I wrong? I think now with my other mods I should be in the high 14's...but isn't TPI as much of a restriction as TBI especially at higher RPM's? I know my tuning may not be perfect...but a whole second loss doesn't seem right to me. Also, my car is in great tune...the l98 has 5,000 miles on it since the rebuild, fully rebuilt rear end and still a good tranny. Is it time for me to go up to the 2" throttle body? I can't think of much else that is a restriction right now at 4000 rpm.

 

Dude, you just need to get that engine to breath. If you have the stock tbi intake on there-you have found your problem. My personal opinion would be to go with the Holley pro-jection manifold and top it off with a 502-6 Holley 670 TBI or a 454 TBI w/ 65pph injectors. Do those mods, grab data using winaldl and tune a chip or get a chip burned. You will be very happy with your gains. Just out of curiosity, what intake do you have on there, what chip are you running, what are your injectors, and do you have an open element?

 

What chip are you using? If it's stock or anything near stock I'm pretty sure that's your problem. I've figured out that SD systems like TBI and 91-92 TPI don't like cam or head changes at all w/o tuning.

It could also be your timing, misc. ignition components (plugs, wires, etc), I've seen plenty of TPI L98s running 15s. In my 305 TPI GTA(mid 14 sec) I beat on a L98 vette, so cars in bad tune run SLOW. I'd even try a little "magic" fuel system cleaner, may help clean the engine out if it was babied/abused all it's life.

I got the stock LO3 intake and stock TBI to run close to 95 mph(94.90) in a stock headed LO3(w/ L98 cam). With stock tune. I'm sure it's(intake/TBI) hurting you, but it may not be the root to your problem.

 

Well I have an Edelbrock performer TBI intake manifold, under an Ultimated TBI, running 65# injectors, and a chip out of a Caprice with an L05 (police package if that makes any difference). Alright...so I may need to get into prom burning...I understand that....but wouldn't a 670cfm throttle body also be holding me back after I do heads and cam. I plan to do those in about 3 months. Other than that...I can't really think of anything...also why would an L03 with a cam...be faster than an L98...if they have the same cam...it must be tuning.

 

And yes i do have an open element.

 

92White RS did you change your knock sensor and your ESC Module when you put the l98 in?

 

No. There are a few guys succesfully running the 330hp 350 H.O. using the holley 670. The only thing that would be holding you back would be the edelbrock manifold you have, as it has the 1 11/16" bores opposed to the 2" bores on the holley TBI.
Also, as camaro89rs355 brought up, you need to change your knock sensor and esc module. Otherwise, they could be picking up false knock and thus retarding your timing.

 

Every tenth knocked off a 60 ft = 2 tenths saved in the 1/4 mile.

I got a 91-92 mph trap speed, that's worth border line low 15/ high 14's there, but with no traction I'm stuck at 15.4.

I'm hoping to run a 93-94 mph trap speed and break into 14's after I put some headers and y-pipe on my puny lo3...

 

No...I haven't really changed my ESC or knock sensor....I don't know if my car even has a knock sensor anymore...I have some sort of broken sensor...I thought it might be the fan switch though...I'm not sure. What ESC and knock sensor would I need exactly?

 

Alright, I went out and bought an ESC and Knock sensor...but am having a problem. Where does the knock sensor go? I thought it would be easy enough to see...but I can't seem to locate it...on different blocks will it be in different places? Also, is it possible there isn't a hole for it? I can't see anything that resembles a knock sensor under my car. I'm looking on the passengers side, by the starter and don't see a thing. If anyone has any idea...I'd be thankful.

 

Middle of the block by the oil pan, passenger side.

 

Ok...I think I figured out my problem...no knock sensor. What's strange is I wasn't throwing a code all the time though. Well hopefully I'll be able to drive my car a bit later if I can find someplace for the knock sensor to go....(seems too small). Thanks everyone.

 

When you get the knock sensor make sure you get one for a 350. YOU HAVE TO HAVE ONE FOR A 350 AND GET THE 350 ESC TOO!!!!!!!!!!!!!!!!!!!!!

 

Alright...I did all that for a 350, took the part #'s that people have given here. Alright the ESC fits no problem. My knock sensor GM#10456288 will not fit anywhere on the passenger side of the block. However, I do see some sort of plug that I may be able to pull out with a socket...but I'm afraid to do so because I don't know what's behind there...oh well. Gotta go try.

 

antifreeze is going to come out that hole but that's ok. It's where it go's

 

Wow! All I can say is that. My TBI was not holding me back..it was the fact I didn't have a knock sensor at all and wasn't getting any spark advance....what a difference it makes. Now my 1 11/16" bores may be holding me back, but I don't care. Feels like a new car now. I want to say thanks to everyone that helped me identify this problem...I was going to waste lots of money on upgrades that wouldn't have meant a thing . I'm going to the track tonight, I'll let everyone know how it goes.