I'm building an engine for my Vega. It weights 2400lbs with the 350 in it. What combo would suit me better? I'm shooting for 450rwhp.. I have the cash to do it (sold one of my IROC-Zs) so even though these setups sound exotic, I can afford it.

327sbc, solid roller, roller lifters, dished pistons with a blower, 150shot of NOS at the loud pedal

302sbc, solid roller, roller lifters, dished pistons with a blower, 200shot of NOS at the loud pedal..

Which would be better, a turbo or a blower? I know turbos are hell to setup but for revs both motors can take it..

Block is a 4-bolt main, 350.. 2-piece rear seal with a steel crank (already have it sitting in the garage).

I'm going to align-bore it, balance the rotating assembly, and buy forged rods and pistons.

Is 550hp on the motor too much to ask? I'm hoping for 600 with the NOS, atleast..

With 450rwhp my estimated times are sub 11s

thanks for the help guys,
Colin
Webmaster: www.GMPerformance.org

 

One more thing...

which motor, the 302 or the 327, would take boost better? They'll both rev about the same (302 a bit higher) but I'm not considering shifting any higher than 6300..

like.. is one stronger than the other because of the bore/stroke ratio or anything?

thanks..
Colin

 

I'd say the motor with a smaller stroke would take it better, but if you're only revving to 6300 I'd say why not just build a 350? It will rev to 6300 with some good heads and it will have more cubes which makes it more torquey from the start. If it were me and I was gunna have a choice of the two I'd go for the 327, just make sure you get a forged or nodular rotating assembly, make sure to balance it, and use ARP bolts.

 

thanks for the reply, iroc5speed

this is my dilemma.. i'm shooting for a good all-around setup.. my problem with this car will be traction.. with 2400lbs, slamming the loud pedal with ANY engine is sure to entice squeals of happiness in the back but I want a good streetable setup that still gets good torque..

i've been considering a turbo setup seriously the last while.. I think that a 327 with a turbo would definitely be a good setup as the lag on the turbo would keep my tires somewhat glued..

i'd rather not go any bigger than 327 as the torque will seriously limit the miles i get on my rubber lol

guys with 450hp routinely run sub 12s but i'm shooting for a good all-around setup.. even though a 350 would be cheaper to build than a 327, i think a 302/327 would suit my better..

i was told to go with the 302 with the 6" rod.. would that help my torque problem if i went that route? i know the pistons/rods are prohibitively expensive if i go that route..

do you think a blower would be an easier swap as Vortec/Paxton offer packages for TPI, right out of the box? a side note, everything is going to be forged, i already have a 350 block with a steel crank so a 350 won't be too hard to work into

thanks man,
Colin

 

If you have money (don't have to reuse parts), and you don't need a whole lot (you know what I mean) of low end torque, then why are using tpi? Just something to consider.

 

Hot damn. 450rwhp in a 2400 pound car is going to put you way past 11s, I would say low 10s probably. Have you thought about a minirammed paxton supercharged 327? :) I'd like to see that one.

 

Just to be cool as all get out, do a Ramjet 502. Aluminum headed big block doesn't weigh all that much more, only $8k ish and all done. You won't break it and it has a good warranty. Plus, you can sell all you have now for a motor to pay for some of it. Just my .02. Have fun.


FYI, you will need a new tranny, even for the other small blocks and new rear-end and driveshaft too. The stuff you got will robably break

 

colin, deciding between a turbo and a blower really is a matter of what you want to use the car for. if the car is ever going to be used in road racing or autocross, then I strongly recommend against the turbo, they can be unpredictable. I think the 327 is your best bet. IT's going to give you enough displacement to get over 450, and it's a good engine. Just make sure everything is forged and I wouldn't waste my money on a 6" rod setup.

 

What's wrong with 6" rods? Too much $/hp? I thought longer rods were more durable than shorter ones and better for hi rpm?

 

I've always thought the 6" rod is shorter. A shorter rod is better than a lonmger rod, it's stronger. But I'm not sure it even matters that much on streetable engines, as long as you get some good forged rods.

 

Which blower? Roots style?

I have been playing with an Engine Analyzer with various configurations of engines, including power adders. What I have noticed is that a turbo seems to prefer a large bore/short stroke engine. The turbo promotes low end TQ (which is nice for a small engine) and with the short stroke (permitting it to rev), it can produce a lot of HP (depending on your boost). A 320 (A Motown 400 block with 350 mains with a 3" crank) was a killer with a turbo.

A supercharger seems to prefer larger displacement motors, especially centrifigual. A 415+ preferred a centrifigual over a turbo at the same boost rating. I didn't play with the Roots type but I believe it would be half way between both.

 

Here's what I'm thinking...

327 forged everything
Healthy solid roller cam
Full roller rockers
Heads?- aluminum? (save some weight)
750 holley
Torquer intake
150 shot of juice
4.10's (at least) out back
Slicks

I would say that engine would definetly put some power to the ground. You are going to have to play around with desktop dyno to find a cam that will work well for high rpm use. I would use nitrous instead of a blower for cost/ease. A turbo setup would be cool, but cost ton and be a pain in your @ss. I would stay away from turbo just because everything will have to be custom made. You shouldnt have too bad of a traction problem, because you can hook and then spray. I would say that the engine would probably see more than 6300rpm, but that depends a lot on which cam you go with. If I were you, I would set it up to scream. I dont have desktop dyno, or I'd try to get you some numbers from my setup. Look at it this way, anything making decent power in a 2400lb car will fly.

Good luck

 

I'm going to start with the stock TPI for now (i have a dremel and will be porting the plenum and base as well as gasket-matching everything) but my goal is to step into a mini-ram..

 

i can't believe all of the replies on this topic!! awesome

85transamtpi is right on the money..

to save weight I'm going to the AFR aluminum 190cc street heads.. they're supposed to be some of the best heads on the block and definitely will make a screamer...

i'm going with a solid roller cam with roller rockers..

not sure on cam lift/duration yet as I need to punch some numbers and see what cc size to get with my heads...

i'm shooting for 8ish:1 NA and around 10.25-10.5ish:1 blown..

everything is going to be forged and balanced.. luckily I have a good block to start with so that should save me some dough..

one of the major issues that i'm going to have is the oilpan clearance. Vegas lack a standard crossmember so the oilpan is majorly modified.. going with a T-56 later will require a one-piece rear seal crank so I may have problems building a 327

I suppose I could use the 1-piece conversio nfrom Summit but I have no idea how reliable those are..

I may fire the car with a carburetor to make sure it runs good and then install the TPI. My TPI is already cleaned up and ready to go, but I need to modify the fuel tank for the TPI sender and pump unit.

the more I think about it, the more that a blower seems the way to go.. a turbo 'will' be a pain in the azz especially when it comes to tuning.. i'd be much better off just buying a blower package from a reputable company that has a TPI/LT-1 intercooled setup..

thanks for the replies, I'll keep you all posted.. i'm pulling the car in to start work on it in a few weeks so it should be nothing but fun fun FUN! by summer

 

I have a question. Why would you run dished pistons instead of flat tops? Would the compression of flat tops and the supercharger be too much?

 

yup..

you can run a blower with like 9.5:1 compression but you ahve to keep the boost low to not get massive detonation..

lower compression == capability to run more boost

as for flame travel, i believe both dished and flat-tops are roughly the same.. domed pistons aren't as good, though (that's what my engine rebuilder says)

 

Things don't add up here

Limiting yourself to 6300 RPM and going solid roller? Limiting yourself in cubic inches and shooting for 450 HP?

Damn, do it easy way, just build the 350. It's not like the extra stroke it has is going to become a torque monster at 1200RPMs and fry the tires out it.

Take the money you saved in building the larger cubed engine, and put it where it counts on the Vega, back 1/2 the thing with a 4link and a narrow'ed 9inch.

 

Big Block equals big power and lasts long. So you believe you should lower compression so you can run more boost? Why, are you trying to break a high boost record? Go with the flat tops and a wiend belt drive supercharger if you want to run the small block. If you can't get enough traction do something about it besides killing your engine power. Taller tires ,less flywheel wieght or torque converter, taller rearend gears. Turbocharger would probably cost much more and be harder to get working right.

 

i'd love to go with a big block..

in fact, i have a set of cast iron square port heads all wrapped up in plastic..

thing is, if i want to do that i really need to cut the front of the unibody off and build a complete frame and that's not fun

i'm gonna go TPI (probably miniram) so i'd rather not get a tall blower sticking outta the hood, heh..

it's gonna be as much of a sleeper as i can get it to be..

boy, oh boy, are the ricers are here gonna be surprised