Hi there Guys. AS I said I am building a lt1 motor for a Turbo. I have many Questions? I hope you guys can help.

First off its gona be a LT1 stock block, stock stroke.
I want to use turbo pistons,
Any Idea what type I should use? Part #?
Also any recommendations on ring Gap?

I was talking about rod length with some guys and Have no idea which way to go?
Should I use standard length rods or should I use 6" rods?
I was told that standard might be better with a turbo? Any Thoughts?

I am shooting for somewhere between 600 to 700 RWH.
I think I may use an alcohol injection system with it.
Any Idea what size injectors I should use?

I plan on building the short block strong! I am having the Top end ported and re-worked. I am lost when it comes to turbo so any help would be great! Is there a sight with this type info on it anywhere? Thx for your responses. Lata, Arkangel77

 

You may want to ask the question in the Forced Induction section on CamaroZ28.com. There’s several turbo LT1s on there.

On my motor, I went w/ JE pistons. I also have AFR heads w/ larger chambers on them to drop the compression. You may want to think about getting a larger dish if you are going to use LTx heads. My compression comes out to almost exactly 9:1 using 64cc chambers and a –21cc dish. I "think" either JE or Wiseco has a -31cc slug. Might want to check though.

I’m using SpeedPro rings in this motor. They recommend .025” on top ring, .020” on second ring.

For rod length, I would go w/ the stock 5.7” There’s arguments to be made for both sides (outward cylinder wall forces, lower wrist pin in piston). If you go w/ a larger dish, I'd definitely run the 5.7 rod.

As far as injectors, with stock fuel pressure (43.5), you can get about 700hp out of 72# injectors safely. You can use this formula to figure injector rates.

(Injector rating * duty cycle/BSFC)*# of injectors

Remember, the injector rating is based on what pressure the injector is tested at. Duty cycle should not exceed 80% (.80). That’s just to be safe. BSFC is the fuel consumption. Turbo motors are between .60-.65, supercharged are .55-.60 and N/A are .50-.55.

Best of luck on the build. Don't forget about the driveline which will be screaming for mercy behind a 700hp motor and getting plenty of fuel to these monster injectors. My fuel system cost be about $2,000.

 

I'd stay with rods around stock length otherwise you might have problems finding low compression pistons with the pin heighth you need.

I'd go 8.5:1 - 9:1.

The lower the engine compression the lower the relative total compression will be on boost.

 

Thanks for the Info Guys! I am learning more about this stuff every day! Keep the replies comming! Lata, Ark

 

Why stock stroke - if you are buying new pistons and rods it is almost no extra money other than the cost of the crank to go 383. The extra cubes will help with spool, etc - always a good thing. A cast crank would still be stronger than stock, though I would consider a forged unit. You can pick up an eagle forged crank for well under 700 bucks.

Pistons - just stick with a 2618 or similar alloy. I would check out some of the JE extreme duty reverse dome pistons - you can probably find an off the shelf for your application. My choice would be JE or CP pistons.

For rods go with an eagle h-beam - for the $$$ you can't beat them. I would stick witha 5.7 on a 383, though you could go with a 6" on a 355. I would just let the piston selection dictate that (what you can get off the shelf).

For rings I would go with a normal plasma moly rings - you can get them from JE, etc. I would tend to shy away from any gapless ring. For gaping specs you need to wait until you get your pistons - depending on the alloy the specs will be different.

I would also suggest going with a FAST/Gen VII DFI, etc. For injectors if you have the DFI/FAST box just go with some 72lb/hr low-z injectors with dual intank GSS340's. Get a decent regulator - rest of fuel system will be fine at that power level.

Compression wise, if you want 600rwhp shoot for 9-9.4:1 (on 93 octane), if you want 700rwhp I would shoot for 8.5:1. Build the compression ratio into the motor though, don't go with a big deck, thick headgaskets, etc. - keep the quench down to 35-45 thousandths. I would also go with 4 bolt mains - you can do it on the cheap if you can find a corvette block.

Really the most important part is the turbo setup and the turbo selection itself, which you didn't mention. I wouldn't go any smaller than a t-76Q trim for what you are talking. Probably I would go with a t-88 and keep the a/r ratio down on the hot side. It would give you room to grow (on c-16). Roomate just dynoed his 383LT1 with a t-88/homebuilt kit, and on 12lbs of boost did 640/655 on 93 - this was straight off the highway, no cooldown, heatsoaked intercooler, etc. Conservative, 25degrees of timing, 11.5:1 a/f ratio. That's an easy 700+rwhp when tweaked for pump gas.

 

this is my take on it
if you want a street monster you build like the turbo regals,very low compression and high boost
7.5-8.0:1 will yeild a pump gas friendly 16-18 psi
with the right intercooler and tuning

now for a street/strip car 9.0:1 with lower boost
on pump gas 11-13 psi and
higher boost on race gas

 

larger cubes is not the answer
it is best to stick around stock if not destroked for race applications
smaller motors turn up quicker which is what you want on a large turbo
duttweiller has built many more small block turbo cars
than anyone could dream and the formula is pretty much the same...small cubes big turbo
job spetter pretty much the same way

there are better areas to invest in on you combination than cubes

 

yes, more cubes is better. PERIOD. The reason why Kenny and Job, etc run small CI motors is due to RULES.

 

I plan to Run stock displacement NOT stroked! I was thinking of 8.5 to 1 pistons and I have spoke with a few Turbo Engin Builders and they said longer rods are better?Thinking of 6" H beam ronds. I am also thinking of running STS turbo with methenaule(???) injection. Still trying to Put it all together? Need to find a timing chain that wont cost me $350+!!!!!!!! LT4 will require new Opti and Cloys is $360 threw Jegs??? Way to Much!!! Thx for the Tips Guys, I think I am getting real good advice and hope to get it streight soon. Lata, Ark

 

Well, if you ask for suggestions and then say you aren't gonna do it, then why bother.


besides, what do I know

Jordon Musser (~650rwhp LT1 on 12psi/pump gas, and knows where to get a good LT1 timing chain for $70)

 

Well I asked for suggestions. I did not mean to offend you? I have been calling folks and talking with folks for a good while now! I never said you were wrong I just stated what I think I will be doing>? Nothing is final yet? I would like to know about that Timing chain if you feal like sharing? As I said B4 thank's for the reply's, Lata, Ark

 

Sounds like you already have decided what you are going to do - why bother to ask question (did PSJ send you here? )




You realize that

1) Turbo spool up is massflow/temp based - a bigger motor *will* spool up the motor quicker

2) What do you mean "the smaller motor will spool up faster" - whichever motor is making more power is going to get to go throught he rpm band quicker.

Only reason to go with less cubes is

a) Class based restrictions on size
b) piston strength

You can get plenty of piston on a 5.7 383 - plus have quicker spool up and better off boost drivability.



Why?




Why? What is your basis for deciding on 8.5:1 as the "magic number"




Why, and in what context? If they were any good the statement whould have to be qualified - no engine builder would sacrafice compression height if it was critical for rod length - esp. on a FI motor. You can't just say "longer is better" as it's all relative. and in a FI setup there are arguments that shorter is better (you have a free flowing pressurized intake - so you can benefit from a quicker intake pulse (shorter r/s ratio) and then get the valve closed.




And you think that will make 700rwhp because......


Timing chain - 95+ opti, electric waterpump, and double roller. should be under 100 for the timing chain.

 

I am just trying to say if you are going to do a turbo, stock cubes will suffice just fine

kenny puts out alot of street cars so does Job
most if I recollect are small cid
it works better overall !!!!!

not trying to start a flame war!!!

 

Chris just laid out plain and simple why more cubes work better period!!!!! what is your reasoning behind smaller cubes!!!! cause you have yet to give us a good reason!!!! why????? because there is not good reason aside from maybe cost and class restrictions!!!!

 

Arkangel77:

the sts kit is not the way to go, if you have a target 6-700 hp car IMO,
if you want to get it because the price is cheap then you are already starting out with the wrong attitude
you get what you pay for.
not saying the sts route is bad, just saying it is better to go with something like a incon(if you can find one) or QTP for a higher HP application, all these kits can easily
yeild far higher HP than advertised...you will end up adding a bigger turbo later ,always happens!!!!
just save up a buy a premium new/used kit
application

 

cost is a good reason,you can spend money elsewhere
if on a budget,
smaller cubes,less torque,easier launching
on asphault,and will sacrifice nothing at the track!!
HP gains from cubes is neglegent with the proper combination
like I said not flaming!!!!! all my opinion!!!

 

Suffice? As in, be "good enough"? That begs the question, what is good enough? Is 300hp good enough? 400hp? 500hp?

On a LT1 if you are already buying a forged crank (which he better if he wants a reliable 700rwhp) then the price difference is <100 bucks between the 383/355 (Since you are buying new pistons also). If you are planning on sticking with the cast crank just cough up 300 bucks and buy a nodular cast unit - still stronger than stock - and for a few hundred bucks more there is no reason *not* to do it.

Now if cranks ran 1500+ like LS1's, then yeah, forget it - but they don't.



Why does it work better overall? As for Duttweiler last time I looked most of the serious GN/T-type buildups were stroked blocks, the SBC's making the most power were all 400SB based units (~427"), etc.

Or Spetter, see
http://www.modularpower.com/wordlsfastest.htm
fastest 2v turbo mustang (modular) - first thing he does is bore and stroke the motor.

So I am infact going to have to disagree with your contention that, when the option is available, they elect to stick with smaller cubic inches. It seems they actually elect to go with as many cubic inches as the piston will support.



Just a punctuation war? !!!!!!!!!!

 

I was planning to do about the same thing when I build my engine. I was gonna stay near stock stroke...maybe go 3.50. But I will be buying a forged crank anyway. So I will probably go 383. You should really consider a forged crank for your setup.

The only reason the stock stroke might be better is you might have a little less torque to deal with...but the more I talk to people it seems like that can be tuned with different exhaust housings and of course electronic boost controllers can do quite a bit to aid in traction.

If you are complaining about spending 350 or whatever for a new opti to convert to a good timing chain...I think you might want to reconsider your plans.

FAST/DFI = 1500-2000
Rearend = 2000+
Trans/Convertor = 1500-3000+

 

chris,
the price is more than 100
you have to have block clearanced also for the extra stroke.
and I think you need a bigger pan not sure though.
ther are plenty of fine details that are overlooked when doing stroker kits
I am sure ther are plenty more


spetters car is still a small 302 cu.
why did he not go bigger than that
and I am sure the buicks can go alot bigger than the
standard 274 kits
these are still very small motors

346 cubes is plenty to deal with
considering what HP some companys have been getting on
stock motors

gothca on the puctuation!!!!!!.........?????????

 

chris how did the 4" MAF turn out
do you have a finished product or are you still working on it????