ok i got a 89 trans am gta 120000 miles on it i was thinkin this rebuild 9.8:1 compression 355ci, TFS G1 heads, flat-tappet hydraulic from Competition Cams (218*/228* duration at .050-inch lift, flow-balanced 24-pound SVO injectors, 52mm BBK throttle body, modified mass airflow sensor ,1 5/8-inch Hedman shorty headers a single 3-inch Race Series Dynomax muffler with dual outlets, do u think i should stick to my regular trans or beef it up to like an TH350 transmission the only thing with that is that it kills your gass mileage and i heard it sucks on the highway people with one what kind of mpg you getting people with a 350 and how so does it suck on the high way and how much do they cost. prob get lik some 3.42 gears, and a HSR to add on top of that how much you think that will end up costing for all of that and how much hp you think i will have post back with comments or things you think i should do different or even a cheaper combo that you think i could get like mid 13s to high 12s and from 350 hp to 400 hp thankyou yes i am a newbie also what suspension measures do think i ll have to do just name them also i dont really have money to blow so thats why i was saying cheapest combo

 

The stock engine came with a roller cam, why would you want to go to a flat tappet? Stick to the 700R4, have it rebuilt by ProBuilt or someone that's good at it.

 

I can tell you when I owned my old speed shop we got $3200 for the long block engine you described (from the article “Ram that TPI” with a Victor Jr intake, Holley 750 carb, Proform HEI, and Accel wires). I had one of these engines as a back up to my 406 and sold it after I closed the shop to a friend for $2600 minus the intake, carb, HEI, and wires. I ended up getting the entire car from him (the 86 IROC) for $2300 after he washed the walls down with an inappropriately burned $500 custom JET chip. Bad for him,, good for me since it only took $400 to get the engine back running. The car was not in the best of shape, so I ended up with right at $6500 in the “Ram that TPI” IROC including the car, engine, interior upgrades, 17” wheels, and ZR Proxy tires. That’s not bad considering that is every nut, bolt, sensor, etc (I kept ALL the receipts) and I know it would have cost at least $3000 more if he had not already had a solid 355 to build on and already swapped to a TH350 transmission.

I’d say keep the 700 if you can find someone that has built others that have held up behind 11 second cars and it’s within the budget. If not, the TH350 is cheap to build and there is usually at least one guy locally that can built one to hold up to racing. However, I wouldn’t want to run any more than 3.23 gears with it if the car is going to see a lot of highway miles. Mileage will suffer, but if you’re tight on cash and worried about gas mileage, you might want to reconsider building a hot rod. Not saying it’s not good to consider the gas mileage into the equation,,, I’m just saying that a good 700 build is not cheap,, and neither are gas prices right now.

If you go the TPI route, you’ll need a serious suspension, budget around $800 (adjustable torque arm, front and rear shocks, rearend guirdle, relocation brackets, etc), plus the slicks. If you go with the HSR and 3.23 with a TH350,, all you’ll need is a set of slicks. On an 89, I think I came up with about $670 bucks to swap over to the HSR (intake, fuel rails, fuel lines, etc), but you can get a few bucks for the TPI system to off-set that,,, so I believe the HSR without a suspension will give the best performance return on your investment. I ran 12.3s with the StealthRam and could get air under the tire at launch,, but I have to tell ya,,, I enjoyed driving the long tube runner set up more. Man,, that thing had BRUTAL throttle response with the modified SLP/TPI system but I could not get enough traction with the stock suspension to get ETs with .3 seconds of the StealthRam.

If all you’re looking for is low to high 12s, you could do that with less expensive Iron Eagle heads and still get away with 10:1 compression. Plus they don’t make the G1s and I wouldn’t recommend any of the twisted wedge heads (G1 or G2) to someone just starting out – the G1s had serious quality control issues and both are harder to set up than standard heads.

The car with the HSR system put down 330 rwhp, but there was a few more in that combination with the A/F mixture being as lean as it was with the stock chip.

Hope that Helps.

Kevin

 

I have the same car with a similiarly built engine. I'm using the TFS 23 degree heads with 10.5:1 compression and a smaller cam. 212 on the intake and 224 on the exhaust with 1.6RR. I'm still in the process of dialing it in. The dyno results today with a corrected SAE .97 was 283RWHP @ 5000 rpm and 311RWTQ @ 4700 rpm. The torque value would be higher but the dyno run was started at 4200 rpm. I have to lean the mixture across the board and then experiment with the timing.

This is enough power to get me into the low 13's as is. I should be able to wring out about 300RWHP. Now this is with SLP runners, Edelbrock TPI manifold and ported plenum and 52MM throttle body. The key here is the SLP runners have one pair fully siamesed and the other siamesed in 1.5 inches at the top and bottom. You will notice that my peak power is at 5000rpm. It was at 4400rpm.

I'm running 3.70 gears and I have serious traction problems even with the modified SLP runners. You should have 3.27 gears in your 9 bolt. Like was said I would leave that alone for the time being. Hope this helps. Allen