NagleMac

iTrader: (1)

I have almost 2k saved to put mods on my 91 RS with a 305. First thing I want to do is hedman shorty headers (68470) whith hedman y- pipe (17470) not sure what cat to get but then to a 2.5in dynomax intermediate pipe which will go to the thrush muffler and 2.5in tail pipes I have, then I want to swap my rear gears from 2.73 non-posi to a 3.42 (Richmond) with a posi, and depending on how much time and money I have left an lt1 cam and custom burned chip, so anyone who has done these things, what are your opinions? And how much will I get out of this? And I have an open element for my air intake

InfernalVortex

iTrader: (4)

Mail order chips are a waste of money. The supporting mods wont really get much out of the 305, because the heads and cam are just as bad at restricting power as the stock exhaust manifolds, intake, and exhaust.

I would put a slightly larger roller cam in it. Maybe a factory LT1 cam or something. And put some 081 heads on it. Then put a cheap set of headers and catback on it. That should be in your budget. Very streetable too and should give the car a lot more pep. You're starting out at a factory 170fwhp... I would assume you could crack 200-220fwhp with 305 TPI heads and a slightly larger roller cam and headers.

The TBI L03 actually has a big advantage over the average crappy LG4 305 because they ran at higher compression, so you can run a larger cam and keep your torque, at least more than you owuld with an LG4.

In general I like your ideas, though. Headers + 3 inch catback, LT1 cam, and 081 heads I think will make that motor all it can be. You'd be in 305 TPI territory then Im sure.

robertfrank

iTrader: (27)

Truthfully you're wasting your time with a 2.5 exhaust.... Go 3 inch or go home, hell I'm even thinking about going 3.5 inch for the 383 swap. With 2k if you want to stay with the 305 I would hunt ebay or craigslist like a madman. You can easily spend 800+ in tuning equipment alone just for starters if you want to get the good stuff. Don't wate your time with the LT1 cam. It's too damn small, Either production LT4 cam or ZZ4 cams work great and are plenty streetable. I've said this a million times and I swear I should be getting paid for this but read my cardomain and learn.

InfernalVortex

iTrader: (4)

If he goes with an LT4 hotcam or other medium-sized roller, he will HAVE to retune it (with all the complications you brought up) or convert it to carb. Then deal with the fact that his 305's power band goes up to 6000 RPM which may or may not be trouble for a stock bottom end like that.

If he stays with stockish style roller cams like the stock LT1 cam, the stock computer could probably do a decent job of running the engine for a while. But the zz4 cam isnt that big, it'd probably work okay too.

Something like the LT4 hotcam would be way too big for the little 305, though, I think.

But at the end of the day, if you want meaningful power gains, it has to come from heads cam and intake. If you cant make the rest of the system work aruond a HCI job, then it's a waste.

I still say get a smallish roller cam and 081 heads, shorties, and a 3 inch catback. If you go cheap you can probably pull that off. robertfrank is right, but you just have to accept that mods that make a big difference in power also make the tune go out of whack and that has repercussions too.

robertfrank

iTrader: (27)

I'm sorry I should clarify, the production LT4 is actually smaller than the ZZ4 cam. The hotcam is the largerof the 3. Either way, there's no getting around tuning.

NagleMac

iTrader: (1)

Ok so if I use the lt4 cam, which heads are the best that I could find used? Then just a small pair of headers with 3in exhaust will be enough? And which intake manifold would be the best? I'm not looking for any drag car, just get some more power out of it before I get it painted just to make it a nice car, and are 3.42 gears enough? Or too much? And with a different cam, will I need larger injectors or anything like that? And I know I'm going to need a tune anyways, definetly not a mail order one though

robertfrank

iTrader: (27)

Ok, did you read my cardomain yet? lol. Honestly I explain all the questions you just asked right there. but....... here you go.

Production LT4 cam 12551142 203/210 - .476/.480 115 LSA

With using 1.5 rockers you'll be just fine. With heads it's a toss up because you really want the heads to line up with both the cam and intake for good power. Mismatched parts suck,lol. Either ZZ4/Aluminum L98 heads work great with minor touch up. The Performer RPM intake is a good intake. I use this combo myself and it's awesome. I'm bascially running a baby ZZ4. Or if you want to go the Vortec route you can do this as well but PLEASE get the Vortec specific intake, a stock style WILL NOT bolt up. You can easily use the stock injectors just get an adjustable FPR and bump the pressure up to about 21-22 psi if you're running a better fuel pump. A TPI pump works excellent here and it's a bolt on swap. 3.42 gears and a good stall will definately wake up your car. I'm running an EDGE 3200 and I LOVE it. Great street manners and the car is a beast out of the hole. Last but not least get into tuning, it's not rocket science. There's just a bit of a learning curve but if a dingbat like myself can do it you can too.

ex-x-fire

I'd put my money towards a vortec 350, 4bbl. vortec intake, & a tbi adaptor. You'll have much better heads & increase indisplacement. You should be able to find one w/ lower mileage if you don't mind paying extra for shipping. These engines will run 200k w/ no problem.

robertfrank

iTrader: (27)

I can agree with this statement to an extent. STOCK Vortec heads are pretty lift limited as far as running any decent cams. I believe they're limited to about .460 lift. Now if running Yellow Z06 valve springs you can go up to about a .550 lift safely IIRC. The only thing I'm not big on with Vortec is the exhaust ports. They suck big donkeys ***** in stock form.

ex-x-fire

The great thing about vortec heads is you dont need max lift to make good power, the have excellent midlift flow, which means the peak flow happens twice, as the valve opens & closes. The vortec exhaust port is certainly better then anything before it w/ exception to the 90s lt engines.
A weekend swap should net him atleast 60 hp & a boatload of torque over what he has now.

SDTransAM

iTrader: (5)

I have done Headman headers with y pipe, and Hooker headers with y pipe. Hands down the Hooker Headers are the superior choice. Fit and finish is 10x better, they are about the same price. And the hookers are every bit worth the little extra price.

Ron U.S.M.C.

I have the same engine and transmission and I went from the 26 spline 2.73 open differential to the 3.42 with the 28 spline Eaton posi. and L.P.W. cover and a Corvette servo.for the 700r4 and the difference is night and day. I love it.I have a few other bolt ons listed in my signature. Mine is a street car and is perfect for what I want. Evey one seems to diss. the 5.0 but any more than that is not necessary for me .The cars geared right,with a posi. and a servo. Has plenty of torque. Can bark and chirp them when I want and launch my back into the seat. No problem. I beleave gears are going to be your biggest and best upgrade. Here's something you can do now to get a better throttle response. Bump your timing to 4* and run a mid grade fuel.

NagleMac

iTrader: (1)

Plans are changing a little bit, I'm gonna be getting a truck so I'm going to get classic plates for my car (no more emmisions) so now I'm thinking long tube headers, x-pipe, and custom exhaust (need some ideas for that) but the first thing I'm doing is deffinetly 3.42 posi, then exhaust and after that depending on funds, either lt4 cam with new heads and intake manifold (no egr) or lt1 cam, stock heads or 305 tpi heads and intake manifold, all depends what I can get for the best price that fits my budget, I'm looking for something that is streetable but can be speedy when you need it to be

NagleMac

iTrader: (1)

Oh and what would be the best thermostat to run this with? I need a new one

NagleMac

iTrader: (1)

I think I've made a final decision, just need to figure out one more thing, is it worth it trying to find a set of 305 h.o. Heads? Or just stick with 305 tpi heads? Then I'll do intake, maybe a reproduction lt1 cam that fits the heads the best, along with shorty headers, matching y-pipe, and single 3 in exhaust, 3.42 posi, stall converter and corvette servo then dump all emmissions stuff except for a good cat.

NagleMac

iTrader: (1)

And will any of this make me lose low end torque? It's not a drag car so I don't want high rpm power, just low to mid range