spdracerIROC

Hey all,

I'm hoping this is the right forum.

I have an 1988 IROC with a 305 TPI, and I'm working on sourcing all the parts to build up a new motor.

The car did come from the factory with an L98 350, but about 5 years ago a fresh 305 was dropped in to replace the original motor that got shelled.
(Why It was replaced with a 305 I don't know)

Anyway, all of the parts match for the 305 (ECM, TPI, Air Intake, Etc.) SO for me to switch back to a 350 may be prohibitively expensive.

I'd like to build the new motor to work with the computer, but I would like to add in a 100-125HP Nitrous boost, and try to get HP in the 300-325 range. (before nitrous)

Right now the car runs quite well, and the engine pulls the car very, very well, and seems to be making quite a bit more than 170HP. (305 factory HP)

I'd run the thing on the 1/4 mile to get a feel for how fast it is, but I'd hate to break it before I have all my new parts.

Bolt on mods currently are 3" flowmaster exhaust, and what look to be a decent set of headers. (The exhaust manifolds do *NOT* look factory, or at least look nothing like the exhaust I had on my 85 V8 Firebird. (The exhaust manifolds are very "tubular" and do not look "cast"). In the next week or so I plan on reworking the airbox to pull in air from behind the fog lamps, and adding a K&N Air filter.

I also plan to have the trans and rear end reworked to handle the additional power, and install a torque converter lock up switch.

I know the stock intake is going to limit how much power I can get out of the car, but I'm not looking to build a 9 second camaro. Mid to high 12's are perfectly fine for me, as the car will still be quite streetable.

So any suggestions on engine parts and specs would be greatly appreciated as I plan to start ordering parts over the summer so I can build the new motor while I have the car stored for winter.


Thanks in advance!

Cronic3rd

Aside from fuel injectors all of the TIP stuff from a 305 and a 350 are identical. 300-325 hp form a 350 osn't hard - big cam, port and polish everything, and custom prom tuning. Forged pistons would be a good Idear for nitrous but a lot of ppl run a 100-125 shot on stock all cast bottom ends.

spdracerIROC

Cronic,


If I understand your suggestion right....

I could replace the 305 with an L98 350 (which is what the car came from the factory with to begin) and only have to change the injectors (which probably ARE the 350 injectors as the person who had the car before me said he only put in a 305 and matching ECM)

So, to sum it up. A slightly built up L98 350 with a computer friendly cam, and a custom chip desgined for timing retard to handle the nitrous boost should do the trick?

Would my hedman's bolt up to an L98 350? I'd hate to have to hack and re-weld the exhaust as I't have to take it to an exhaust shop to have it done, and no exhaust shop in their right mind would touch my IROC as it has no catalytic converter.

Thanks much for the reply!

Cronic3rd

yup. but bigger injectors would prolly be necessary anyway. BTW the ECM is the same between the engines - the PROM might not be though.

yup. your headers will bolt up to any chevy small block from a 265 to a 434.

spdracerIROC

Whoohoo!!!!


Cronic, you just made my day...

So I'm looking at my motor, a chip, and bigger injectors. That'll free up some cash for having the trans and rear axle worked over.


Thanks again!

Cronic3rd

A short block, PROM burning software, and bigger injectors. The TPI 305 heads with a full port and polish and bigger valves are pretty good. And it is better to get the prom burner and learn to use it than to pay some one to keep burning custom chips every time you change something..