Hi guys,

Originally I was going to do an LSx swap into my car, but after thinking things through, I've decided I'm not going to do that. The LSx is a wonderfully smooth motor, but I don't want smooth - the beautiful rumble and exhaust note of the earlier motors just feels too good. Not to mention...I have lots of good parts on my motor that I can reuse, and I like the "simplicity" of the TPI engines.

So my questions are as follows:
-what is the largest "direct replacement" block I can get? By "direct replacement", I mean that all the accessories, distributor, heads, intake, oil pan, etc will work just fine when swapped over (currently have a 305 TPI).

-I definitely want to keep the TPI setup - what would need to be modified for it to work with a larger block? It is pretty much stock except for Accell #19lbs injectors.

-where is a good place to get the block with a balanced rotating assembly (I'm also gonna need low compression 9:1 pistons so I can supercharge and still run pump gas)?

-is a T-56 capable of handling over 500hp? If not, what are my options with regard to manual transmissions?

-what will I need to do to beef up the rear end to handle 500+ hp? I want something that will work well around a track as well as on the strip (something comparable to the posi I currently have...no solid axles or anything like that)

Any opinions/advice is welcome and appreciated.

Thanks,

--Mike

 

400+ cubic inch small blocks are getting pretty common these days. 434 and 454 are often built. And, the TPI will bolt to either of them, along with all accessories.

That's not the issue. The issue is what a TPI system can support. If you keep things like the base and runners, about the biggest it will support is a 305. Of course, the factory put the same base & runners on the 350, so that should tell you something.

If you're willing to upgrade the base & runners, port the plenum, and get bigger injectors, a 350 will easily run well with TPI If you go bigger than that, you need to consider a complete upgrade such as Super Ram, Stealth Ram, or Mini Ram.

As for where to get a complete, balanced engine: Too many possible sources to list.

A T56 can handle about 500 HP, but the better T56 is the Viper version. Bigger input shaft.

A 9-inch or 12-bolt rear end, such as is available from Strange or Moser, will handle the power.

Whatever you spend on the engine, figure on spending at least that much more on the rest of the car (drive line, suspension, etc.).

 

Hi,

Thanks for the reply, that helped me get a good starting point for doing some more research.

Why wouldn't the TPI work on a larger block with the upgrades you mentioned (base, runners, etc)? Is it because it will be restricting the airflow at such high volumes? If so, would slapping a supercharger on that sucker possibly alleviate the air restriction issues? I'm trying to go as sleeper-esque as possible.

Turns out the upgraded intakes you listed are much less cost prohibitive then I previously thought they would be, so I'll maybe go that route if its easier. I want to keep my stock Trans Am hood, so I think the Stealth Ram is out. Will the other two fit under my hood?

Is the stock ECU capable of dealing with a larger (> 400) block? What about a larger supercharged block?

Also, I just wanna make sure - the engine mounts are going to be the same for every size small block, right?

And oops, I forgot I wasn't posting on the regional boards this time - what I meant was:

-where is a good place to get the block with a balanced rotating assembly in Southwestern Ontario


Thanks!

--Mike

 

Oh, one more thing - will my stock heads work alright on a larger block? I would eventually do some work on them, but I just want to get something moving for the time being.

 

ok...this is possibly a stupid question, but here it goes anyway:

what is the difference between my 305 and say, a 350 or a 383? Is it just the crank and rods, or is there something else? Cuz if that's the only difference, I might as well just stroke the motor I have, no? No point in getting another block if theres no difference.

Is there a big difference between a 2-bolt and 4-bolt main? I've heard there is, and I've heard there isn't.
'

 

Okay - I'm home with a headache so I'mna try to answer as much as i can for ya buddy...


The 305, 350, and 383 all share the same rods (typically 5.7 inch)
The 350 and 305 share the same crank and rods (3.48 stroke, 5.7 inch rod)
The 383 and 350 share the same block (4 inch bore)

As far as your use of a supercharger to 'help' the low-flow-TPI problem - its shaky ground you're working on. Yes, the TPI system will make more power with the supercharger, but forced induction doesn't make crap heads flow any better or crap runners flow better. Buy a good set of heads and superchrage THOSE and you'll always make more power than supercharging crap heads. I know that sounds basic, but its true.

I would suggest starting with something simple that has been done before. A 383 is a relatively easy build (requires very little "extra" engine building knowledge) and can yield awesome power. To hit 450hp with a TPI 383 isn't that tough, plus you'll make real nice torque. PROVIDED - that you upgrade the induction. An aftermarket system is a must if you're going to run more than 300cid and 4500rpm, otherwise your motor will be held back big time. Others will tell you that is not true - they are wrong. Without massive modification the stock TPI system isn't suited for serious performance.

Good luck and do your research. Always be leary of what people say and in the end - make your own decisions. Sometimes its good to have a friend who's done it before too...as long as he's fairly competent. lol

Tyler

 

Ok...this is what I've decided: when I get to the engine modding, ill start with a 383, aftermarket intake (not sure which one yet), T-56, new chip, and swap everything else over from my current setup (accessories, heads, accell injectors, etc).

after I have that all working, ill either get new heads or do some work on the ones I have.

and then finally, forced induction and a new rear end will top it off.

all of this will happen after my suspension and frame stiffening work of course.

does this sound like a decently solid plan of action? am i missing anything major (besides the barrage of "little things" that will go wrong along the way haha)?