pauldana

got a 95 ta and my sons and I are thinking of doing a rebuild on the motor and we are throwing around the idea of putting a super charger on it... we want to build it first as a N/A, and put the SC on at latter date, but in the mean time we want to N/A engine to be built out as much as possible, but not prevent a SC from being put on later.

Questions:

Cam, what would be the difference in cam for a SC engine and a normally aspirated?

pistons, what would be the highest C/R to go with?

thx

superstreet

"Blower" cams are usually split duration (the exhaust is retarded) so the pressurized intake charge doesn't go back into the intake.

How much boost do you plan on running? I was running 30 lbs of boost and my compression ratio was 7.9:1. On a stock type compression (no more than 10:1) I wouldn't run more than 6-7 lbs of boost.

Hypereutectic pistons,the term hypereutectic means that the casting of the piston has a higher level of silicon in it.

What we call a regular cast piston is a eutectic. The 'hyper' part just means there's more than 11% of silicon in the piston.

By using higher amounts of silicon in the casting, the piston has better thermal characteristics than that of a regular cast piston. IE, it's more resistant to melting from heat. Kinda like a forged piston.

A forged piston is just that, it's heated to a very high temp after it is cast. This causes the aluminum to become very hard. They have the highest level of heat resistance. That's due to there expanding ability.

Because of there ability to expand, you must allow more clearance so they don't seize themselves to the cylinder walls as they heat up and get bigger. And they usually require more ring gap because of how small they become when they cool. Otherwise the ends of the rings would be touching at start-up, and that would be very very bad.

They don't like nitrous and supercharging.

A big advantage with forged pistons is they generally result in a more ductile material, with the effect being the piston can take a higher level of detonation before failing

Fastbird

For the LT1, the split duration cams work great both N/A and Blown, so find a cam that you want and keep it for the blower.

How much boost do you want to run, or rather, how much power are you looking to make. If you plan to go over about 6-7 lbs of boost, DEFINITELY used a forged bottom end to include pistons. If you're not planning on boosting too high (around 14 lbs tops), I'd recommend building the motor with about a 9.5:1 SCR and spec the cam out to keep the DCR up. This will keep it from becoming too sluggish N/A and off boost.

pauldana

I am delving into an area I am not very familiar with, I have become pretty good with NA cams but have never studied SC cams...I was able to get 440+ hp at the rear wheels in my NA 383, but my boys got a 95 TA and they are wanting to end up some 100hp+ more, so I was thinking a SC

what cam would you suggest? or would you stick with NA to achieve around 550+ at the rear wheels?? thx..

Fastbird

FI definitely. IMO that's going to be too radical of a N/A motor to make 550 at the wheels. YOu're talking a HUGE amount of cash invested into the heads/valvetrain and the addition of a rather large solid roller to make that kind of number. NOT a streetable car at that point.

Do a 355, stock ported heads, mild cam (in the 220 to 230 range), couple of small fuel system upgrades, and a D-1SC kit pullied for about 14-15 lbs of boost or so and your son should easily see 550 at the wheels.

superstreet

pauldana

We are leaning towards N/A... I got over 440hp and 436tq at the rear wheels on my 383..... I understand you can take these engines to 400ci, so is 500hp really that far out?

my vett is very steerable at 440hp.... and I am running a hydraulic cam..... but it sure would be nice to run a small S/C on top of that....

pauldana

Thank you, I would consider myself pretty knowledgeable about N/A Chevy small-blocks, I have built over 15 of them.... its the S/C that I have no experience with... But your write up is VERY good... thank you

Fastbird

Getting them to and over 400 CID is a chore in itself....you're starting to press the limits of the thickness (or lack thereof) of the cylinder walls at that point. Remember that the extra cubes aren't going to do you squat without a top end that will support them. It will take rather radical measures to get to 500 RWHP N/A on an LT1, and done reliably. Admittedly there are exceptions to the rules, and one that I can think of is a N/A 355 with an Advanced Induction 200CC CNC head/Solid Roller cam package that made around 470 RWHP / 400 RWTQ, but for as streetable as you want to call it the thing had to turn over 7K RPM and idled at 1400 for a stable idle (there's a vid floating around). Not what I'd call overly street friendly. More cubes, bigger aftermarket heads, larger SR cam and you're at 500, but with sacrifices. Then with those kinds of RPM's required you start running into stability and reliability issues.

Just my $.02 though.....I've only been around LT1's for a decade now.

RapidRick

Great Thread, with stellar info from Superstreet & Fastbird.

I know funds will be an issue, but how about a pre owned, No Adder LS2 or 3 conversion?.... anyone? 500hp+ is easily doable with no adder.

No disrespect on your thoughts gents, but heck my '01 LS1 puts out 426 RWHP with Heads/Cam/Bolt ons, and its a 17-23 mpg DD.

On a Mustang Dyno, it's 366RWHP. Full weight Formula and I run my car in our Corvette Challenge Series at PBIR. (www.racepbir.com) It has run 11.80's in cool air under 70* with a 180lb.driver & 11.90.s with my 275#

I'm just a fan of these motor's, and the availability and swap-in are sometimes more affordable than expected.

Best of luck whatever you decide Paul.

Here's something for sale that I caught on a sister site:

http://www.ls1tech.com/forums/florid...ort-block.html

pauldana

Yea, i am worried also about the thickness of the walls.... i understand a good top end, my 383 kicks... and its the top end... over 440hp at the rear wheels...and I was under the impression you can get more out of these engines than gen 1 engines in my vett, but i don't know..... is this a LS1?

thank you, but for me and my boys, the fun of the car is the project, when you buy someone else's work.... you can never look at it the same.... se we do everything.... our hobby, we have about $5k projected to go towards the engine.... this is there 2 year project, they are 15 and 17...but thank you again...

RapidRick

So fine, you and your boys can look into building an LS based motor utilizing a 6.0 iron truck block.

Also, Patriot sells a great pair of heads for around $1200. I have some info on their offewring vs. AFR heads here:
http://edigras.iweb.bsu.edu/headscam.htm

Good Luck.

pauldana

, Thanks... I would suggest you do some searching on the patriot heads, its all bad, some of the worst heads made on the market as I undrestand, they flow worse than Gen 1 SBC SB l48 heads, along with a deluge of other problems like engines blowing up on the trak...do a search here on CF C3 section.... I understand the vortec, i think, heads that are on there can be ported polished and port-matched to be as good as any AFR.. ,,, if we do change heads I will be looking at the AFR's but World makes some very good heads as well... my sportsman II flow much better than Edelbrockes RPM heads... of course mine have been ported polished and portmatched...
the thing that i am giving the most thought to is the valve train, and wondering just how many titanium parts will be necessary for a 7K RPM

I figure the Beehive springs, TI keepers and and clips, along with aluminum RR.... but I am in hopes I can skip the TI valves...

But thank you again for the input...

superstreet

Nice. At least you know the ins and outs first. I am building a N/A for my Camaro right now.

Just a base line,anything about 6-7 psi you can get a way with a "stock" set up. Any more boost than that you will need forged parts,split cam,(roller cams help a lot),etc......

I agree with Sean (Fastbird),you are better off to stroke a motor,like your 383, than to bore it out more.

pauldana

From my reading, these blocks do not have a problem with a bore to 400... that is of course in conjunction with the 400 crank to get it to the initial 383...we are planning a 6500RPM red line, with the ability to spin to 7K..... I think we can get a good strong 450tq at the rear wheels, and if I can keep that tq through 5500, that would give me hp=(tq*rpm)/5252 472hp now if i can keep that tq to 6K RPM I would end up with 514hp... this is where we are aiming .....so the valve train will have to be light to rev to this without float...

RapidRick

No Patriot problems here. 12k+ miles and 100+ 1/4 mile passes.
In the Points, and workin' well in our Corvette/GM+ Challenge Series at www.racepbir.com

To each his own I guess.

Good luck to you.
An LS based motor is just a consideration for you and your boys.

pauldana

Thank you

as far as i have been told so far is the only difference between a LT1 and LS1 is cam and higher compression... is this correct? and I have a LT!???? correct? again, i am a GEN 1 guy...

superstreet

The LS1 is a totally new architecture by design.

LT1's were available from '92-'97. '96 for the vette,then LS1's were installed. F-bodies had LT1's until '97.

Your '95 TA has a LT1.

pauldana

what is the difference? any major build differences form Gen1 that I should take into account?

Fastbird

Reverse flow cooling is the biggest departure from the GenI stuff. Coolant goes through the heads first.