12 sec Street mannered Tpi Cutlass build

[Bowtieheart]

Alright guys, so after much much reading and adding costs up and seeing which route would be easiest, I've decided to go with the 5.7 Tpi as my base. Another reason I chose the Tpi route is because I can buy a complete late 80's Iroc for around $600-$700 with stock wheels🙂 which I also like. I'll be able to pretty much have everything I need to have the car refereed here in Cali. Now I have noticed that the aftermarket intake mani's don't have a spot for egr, so I'm going to look into getting a ported stock intake mani. I've never built an engine before, nor do I know the EXACT specs i'll need, so that's why i'll need your guys help. There is a local, reputable machine shop that will be doing the work for me, whatever I feel like I can't do. (mainly the bottom end work and porting and polishing the heads.) Enough with my ranting and on to the build. But first, check this out, and if any of you know this guy, or are this guy, what the heck does that Monte have, lol very impressive. http://www.youtube.com/watch?v=zfjkIZOzMOw

Engine-5.7 Tpi bored over to 355 with about 10.5 compression
Intake mani-Stock, ported
Heads-Not sure whether to go Corvette aluminum tpi with 202 valves or just regular tpi heads with 202 valves and either will have port and polish.
Cam-Not sure but needs to be street friendly. (Don't want it sound like a dragster)
Headers-Hedman Longtubes?
Exhaust-X-pipe with true duals(just not sure the oiping size since it'll be dual)
Ecu and tuning-Manley Performance here in Socal
Injectors/fuel system-Not sure what all i'd need to upgrade or add.
Trans-Would love to go manual but might have to stay auto, depends on what deals I come across, so ideas for both please.
Drive shaft-Stock or are the lightweight ones worth the extra dough?
Rear end-Monte SS with Posi and 342 gears? Want to get AT LEAST 20 mpg hwy.
Tires-Suggestions?

 

[DRIVEN]

Since you've decided on a TPI, my suggestion is to build for torque. That's what the TPI was designed for and that's what get's your car moving. Rather than fight it and target peak HP, why not embrace it? If I were in your shoes, I'd probably add a stroker kit. Since you're planning to have it rebuilt anyway, the added expense is marginal. I'd probably not waste any money on stock heads. The L98 heads aren't famous for performance in the first place. By the time you add larger valves, good springs, and any beneficial port work you could probably just buy better aftermarket heads for the same money. Remember, an engine should be a package. Before you buy anything you'd be well served to talk to your builder, cam tech support, and head manufacturers. Relatively speaking, the TPI is a low HP engine -- It's their inherent torque that makes them feel quick.

Not an inexpensive example-
http://www.superchevy.com/technical/eng ... induction/

 

[Bowtieheart]

I was considering the 383 route but I forgot where exactly I read it but I believe it was on the Third Gen Forum and they were saying how tpi/383 combo don't work so well together. Plus I was thinking since the tpi is a torque beast, why not just try to focus more on top-end, since torque will be there. Plus I do know that too much torque will also be a bad thing when trying to get out the hole. Don't want my first gear to be pointless.

 

[jae]

The main thing people miss / forget is that the TPI is designed and based on the 305, with its small bore and puny ports. Remember this was at a time when you had to deal with ever-tightening emissions and most manufacturers were seriously looking at downgrading engine displacement and # of cylinders (not unlike today). The entire intake system (throttle body, main plenum, intake runners and lower intake) is small in terms of flow; I mean, why have something that has hella intake flow when it will only get strangled by the small port in the head and small valve. The runner length helps make up the hp deficit, making good torque, especially on the 350.

Again, since most guys/gals don't know this they just go straight to stroking it, completing head work w/ bigger valves, put in a hotter cam and are disappointed when the engine falls on its face. The intake can't keep up with the improved breathing capability of the long-block. It's similar to when folks over or under-carb their engine, or keep a restrictive exhaust, or have a nice engine package but have a crap-tastic ignition.

Driven's statements and article link were very good and makes that point. In the article they actually explained this achilles hill and "corrected" it by extrude honing and doing some porting work on the entire system as well as going to a larger throttle body. Honestly I would do that even if I wasn't going to stroke it to a 383. I was going to suggest trying to find aftermarket runners or have the ports / runners ported. Upping the injector size may help, as well as getting the ignition in order. The stock HEI gives up the ghost around 4500 ~ 4800, same rpm the intake runs out of breath.

God luck and keep posting

 

[Bowtieheart]

The main thing people miss / forget is that the TPI is designed and based on the 305, with its small bore and puny ports. Remember this was at a time when you had to deal with ever-tightening emissions and most manufacturers were seriously looking at downgrading engine displacement and # of cylinders (not unlike today). The entire intake system (throttle body, main plenum, intake runners and lower intake) is small in terms of flow; I mean, why have something that has hella intake flow when it will only get strangled by the small port in the head and small valve. The runner length helps make up the hp deficit, making good torque, especially on the 350.

Again, since most guys/gals don't know this they just go straight to stroking it, completing head work w/ bigger valves, put in a hotter cam and are disappointed when the engine falls on its face. The intake can't keep up with the improved breathing capability of the long-block. It's similar to when folks over or under-carb their engine, or keep a restrictive exhaust, or have a nice engine package but have a crap-tastic ignition.

Driven's statements and article link were very good and makes that point. In the article they actually explained this achilles hill and "corrected" it by extrude honing and doing some porting work on the entire system as well as going to a larger throttle body. Honestly I would do that even if I wasn't going to stroke it to a 383. I was going to suggest trying to find aftermarket runners or have the ports / runners ported. Upping the injector size may help, as well as getting the ignition in order. The stock HEI gives up the ghost around 4500 ~ 4800, same rpm the intake runs out of breath.
viewtopic.php?f=69&t=48980&p=415037#p415037
This is great info and I'll be posting this on the Official build thread🙂 thanks

God luck and keep posting