3rdgenmaro

iTrader: (9)

I figure this will be a good little place to post on this. For both information and for help as it progresses.

First off, lets make it clear. This is a pure stock class car. Their are specific engine rules that must be followed.

Having said that, I have already started and seen decent success with the stock 91 LO3, but being what it is, I know there is ways to make it better and still fit the pure stock rules.

Currently, it is just the stock TBI 305. EGR has been removed, stock chip, smog removed, open air cleaner, and the factory Y (T) pipe and manifolds. I am running an underdrive crank pulley only to slow the water pump down. At this point, since it is middle of the season, I am not going to go internal to the motor, but if things go well, this offseason we will.

Per the rules, I must run the stock intake. Unless there a GM cast iron TBI intake out there better then this one, Im stuck here.

I also must run stock cast iron exhaust manifolds. Here is my first upgrade I plan. Toss the L03 manifolds and T pipe and put on a set of the L98 manifolds with a short section of piping (no Y). I already have the manifolds thanks to John in RI, and will have them on by the next time I get the car on track. Im interested in seeing what difference they might make.

Im new to moding TBI, so Im still doing a lot of research on it. Like swapping to 350 injectors, tweak fuel pressure, etc. These seem like areas I might really need to address since I am running the motor pretty hard (3800-4300) for 8 miles. Might be needing that extra fuel.

Im trying to make smart decisions that fit the rules as written.

morgsie

iTrader: (1)

I thought all stock tbi intake manifolds were aluminum... Apparently the L05 truck intake flows the most. Also can you run any stock exhaust manifolds? If so the 1-ton truck manifolds of similar vintage are the ones to go with. Just bump up fuel pressure rather than swapping injectors, unless yours are bad. You will need burn a chip(s) to take full advantage of any mods you do. the ecu can only adjust so much in stock form. Upgrading to EBL is a good idea as it is installed into the stock ecu case and appears stock. It is also less of a learning curve vs chip burning/emulation.

Fast355

iTrader: (2)

Actually LT1 manifolds are better than truck manifolds by far.

3rdgenmaro

iTrader: (9)

Yeah the LT1 manifolds are nice, but I didnt want to push the rule that much. But, maybe in the future......

As far as the intake manifold goes, I dont know. I havent checked, never had one apart. I just assumed it was cast. Either way I still pass the rules since it is factory, but showing up with "Edelbrock" on the side might push it. I'll look into the L05 intake.

Fast355

iTrader: (2)

There are like 4 different TBI manifold castings. Look for an 87-95 fullsize van as most of then had 350s and the taller intake. Could you run stamped 1.6 rockers?

92RS_Ttop

iTrader: (3)

As mentioned above, the stock 88-98 truck intakes are aluminum. At least the one on my 94 was. I don't know if they really do flow better, but they are lighter. I'd also recommend checking out tbichips.com. They have some great info on modding the stock TBI unit for more power. The site is aimed at the truck crowd, but the principles are the same.

3rdgenmaro

iTrader: (9)

Thanks.

Rules say stock rocker arms. But, I have seen some stock appearing stamped 1.6s. I have an l98 cam I thought about putting in at some point.

morgsie

iTrader: (1)

I have a set of stock stamped steel 1.6 rocker arms that will be coming off my car in the next month to get replaced by roller rocker arms if you are interester.. i believe they were an elgin part... http://www.fullsizechevy.com/forum/general-discussion/performance/17534-1-6-stamped-steel-rocker-arms-found.html

3rdgenmaro

iTrader: (9)

Well I had planned on having the L98 manifolds and better piping by the time I got the car back up and running. But since things take longer then you expect and time is always shorter than you need, the L03 manifolds and about 6" of the factory piping are still in place. Only change is no longer having the factory "T" pipe.

gearheadotaku

iTrader: (1)

I have L98 manifolds and Y-pipe on mine along with a LT1 cam ('92 Vette) and chip to match. Pulled a full second off my 1/4 mile time, a shot on the dark says 200hp. I'd skip the L98 cam and get on of these if its allowed.

3rdgenmaro

iTrader: (9)

Too much of a push. I couldn't claim a 91 cam with the LT1 cam. Might never find out, but if I do, I want to have some ground to stand on.

3rdgenmaro

iTrader: (9)

Finally was able to get back on track this Saturday night.

Only engine change was with the exhaust. Only a minor change, but sounded better and felt alittle better. May have been in my head, but felt like it was just a tad stronger. Before I had the factory crappy T connection intact. Now I only have about 8" of the factory pipe after the l03 manifolds.

Still got to get the car painted and do a couple minor things, but hopefully I can get the l98 manifolds and some better piping on by end of august.

3rdgenmaro

iTrader: (9)

Well I never did get the l98 manifolds on. Been too busy putting a fuel cell in. I still plan on slowly moding the car through this season though. I haven't done anything to the motor. I did talk to brian at TBIchips, but until I do some more work, there really isn't much point in a chip right now. I did buy an injector spacer, but only since it was $13.

I really want to get the manifolds on soon, but Im not going to hold my breath. I had to change tracks and Im not sure how reactions to the car will be.

mikeyt

Where do you race and what kind of racing is it, sounds really cool. Sounds like vintage racing?

3rdgenmaro

iTrader: (9)

Built the car for wythe then they cut the class. Probably play around at different tracks this year getting seat time. Then build a more competitive car this winter. Will be at rolling thunder in ararat va in a couple weeks hopefully. Do you race?

92RS_Ttop

iTrader: (3)

Are you allowed porting the heads and intake? Or swapping to different year stock heads? Not talking Vortecs, but the 416 heads used in earlier thirdgens. You could pick up a set of 416 heads and port them and the intake to match. Supposed to make a nice improvement. Maybe a little work on the exhaust manifolds too to open them up a bit. There's also things you can do to the TBI itself, like grinding the top ridges off around the inlets, shaving the throttle blade shaft, or even having the bores opened up and using bigger throttle blades. The 88-98 trucks with the 454 engine has larger bores in the TBI, IIRC. Could you maybe swap to one of those or does the TBI have to come off a thirdgen? It's also possible to make the stock fuel pressure regulator adjustable, or you can buy one. Just some thoughts from when I had my 94 truck and was looking into making a little more power.

3rdgenmaro

iTrader: (9)

No porting. "Stock size valve for make and model" No 993. So yes, can swap heads.

Vague rules really

mikeyt

I don't race, I'd like to though. There's a auto cross track/events at Little Creek amphibious base in Norfolk Virginia that hold stock and several upgraded classes from mild to wild

DynoDave43

iTrader: (11)

Nothing says you can't go with undercut stems (if you don't have them), or a 5 angle valve job.

3rdgenmaro

iTrader: (9)

That is true. Right now Im going to see how the season goes as is, with only minor upgrades. Get some seat time. If all goes well, I'll probably push the rules a lot harder this fall.

3rdgenmaro

iTrader: (9)

Finally got back on track. So far the car has more in it then the driver does

But with the few things I have done, you can tell a difference in the motor. So far only changes have been injector pod spacer, tweaking the base timing, and running a flat base air cleaner. Those and open exhaust are definitely noticeable off the corners.

I have the passenger side TPI manifold ready to put on once I get a piece of pipe for it. Driver Side I have to drill out the broken studs first. Hopefully the bolts in the heads come out fairly easy. Really don't want to break any of them off.

chazman

iTrader: (4)

I've always wondered what a full on factory N10 exhaust would do for an L03.

dmccain

iTrader: (2)

Ive been thinking hard on L98 manifolds and a magnaflow y-pipe to go on mine for a while. Let me know if the manifolds seems to help your L03 out. Supposedely the N10 exhaust was worth 25HP difference on the G92 LB9 cars.

3rdgenmaro

iTrader: (9)

From what all Ive read, it should. I'll let you know when the time comes.

3rdgenmaro

iTrader: (9)

So a couple more races have come and gone, and Im starting to really tell where im down on power compared to others.

I haven't swapped manifolds yet, but may start trying to soak the bolts this week.

5 races left in the season, Im debating on taking one weekend and putting the L98 cam I have in the motor. I have another set of heads somewhere at my dad's, I need to see what #s they are.

How good/bad would the stock l03 tune run with the l98 cam you think? Not interested at this point in putting $200 into a chip. Might be going carb next season, not sure, don't want to waste the money. Opinions?

3rdgenmaro

iTrader: (9)

Decided in the next 2 months Im going to swap in the L98 cam and manifolds. Along with a second hand TBI chip that was made for a LT1 cam.

Also have to go from t5 to auto, so that will skew the results some. Will be interesting though.

DynoDave43

iTrader: (11)

I will anxiously await your results.

From what people have said about the L03 exhaust, the manifolds alone should make a noticeable difference. Replacing the peanut cam will be another plus.

Schurkey

WHICH auto? I'm hearing good things about a PROPERLY REBUILT TH200 in circle-track applications.

Light, low rotating weight, and a deep first gear. Not very strong, but you don't have much motor.

3rdgenmaro

iTrader: (9)

700r4. Already have one and going the cheap route.

One of the hot items right now that I have heard is taking a turbo 350 and swapping 2nd gear with a 700r4. Or something along those lines. Majority of cars are 70s Camaros. I don't know all the details on that. Rules don't allow it, but you can only claim transmission, you cant protest it.

But did the 3rd gen ever even get the 200r4? Not legal if not.

RBob

iTrader: (1)

The '89 TTA got the 200-4R.

RBob.

Schurkey

I was referring to the "old" TH 200, not the 2004R. But I suppose that wouldn't be legal anyway.

3rdgenmaro

iTrader: (9)

Ah, I see. It is going to be interesting this season I believe. Im just starting out and this will be my first long season. Never been through the protest part. Could get interesting on a few things. Especially since not many people know the 3rd gens.

RBob, I didnt know that. Thanks for mentioning it.

RBob

iTrader: (1)

The TH200 was used in the early 3rd gens. Then the 700R4 was introduced and used through '92. The '89 TTA was a different beast as it used the Buick 3.8l turbo engine. Hence the use of the 200-4R with it.

RBob.

3rdgenmaro

iTrader: (9)

Installed the l98 cam this weekend along with a junkyard 700r4. Still have to button everything up and build an exhaust. Hope to have it fired up within the next 2 weekends.