came across a brand new Jasper Performance Class II verson of the 5.7 LT1 for about half the price.. how do you all feel about these motors? and do any of you have one??

Jasper Performance Products
1992-1997 LT1 Chevrolet
“Class II Version - Chevrolet 5.7”
Version Description:
The Class II Performance engine is for the serious performance minded person who needs power for a
specific application. These engines are built with heavy duty performance in mind. Special components
and procedures are selected and matched to obtain maximum performance for your application.
Not intended for use on pollution-controlled
motor vehicles.
340 hp (estimated) @ 5000 rpm • 383 ft. lbs. Torque (estimated) @ 4000 rpm
Version Applications:
• Performance oriented cars and trucks
• Street Rods and restored muscle cars
• Small/medium size engines requiring
good low speed torque
• O.E.M. replacement
Part Specifications:
• Approximate 9.75:1 compression ratio
• High performance rod bolts and nuts
• High rev lifters and performance valve
springs with retainers
• High volume oil pump
• Cloyes timing set
• Flat top hypereutectic pistons and moly rings
• Harmonic balancer
• Screw in rocker studs
• High performance stainless steel valves:
1.94 Intake; 1.5 Exhaust
• Class II camshaft
• High performance bearings
• High performance head gaskets
Machining Specifications:
• Kolene Salt Bath cleaning
• Three angle valve seat machining
• Precise surface finish measuring
• Square decking of block
• Main saddle align honing
• Electronically balanced engine assembly
• Torque plate honing
• Computerized boring
• Precision crankshaft machining, oil hole
chamfering and polishing
• Live testing

 

They are a high production motor shop, performance is not what I would call it. No brand name parts, and cheap labor...you get what you pay for.

 

Not much in the way of a "performance" engine. They have dropped the compression ratio from the stock 10.4:1 down to 9.75:1. They have kept the stock valve sizes. Most people will recommend strongly against a high volume oil pump with a stock pan. They have given very little real technical info.... most of it is advertising hype and BS..... "Class II" is advertising, not a technical spec. What have they done to the heads? What cam specs? Sounds basically like a stock rebuild with the wrong head combustion chamber volume.

 

yeah i may have to get more specs on it

 

On top of Fred's comments 340hp on an engine dyno is likely LOWER than the GM engine would make tested in the same manner.

One REPUTABLE performance engine builder's 440hp motor is known to only put 32Xrwhp down. You need to understand flywheel vs. rear wheel numbers.

 

Are you talking about Go*en

Hey Sinister could you told us what is the price tag for this beauty

 

i think its 3600 from jasper.. my thinkg is if there stock motor is stock spes and this is better it should have omse Hp gain over stock...?

here is the list http://www.jasperengines.com/pdf/Cla...-5.7-340-L.pdf

 

anybody else?

 

Do the machining poorly, lower the compression, use substandard parts and it would be pretty easy to deliver a weak motor like this.

The stock motor is rather well put together with pretty good parts. I would call a budget rebuild by an average shop a step backwards from what GM gave us, and this is a "budget performance" rebuild from a poor shop.

If you are that set on it buy it, but expect to hear "we told you so" when you get a weak motor plagued with problems.

 

To give you an idea. The lt1 is rated at 275-285 in are car's stock from GM.
On a engine dyno stripped of the acessories it makes 350ish. RWHP is in the 240-260hp range. Most engine builders give you latter power output. Like how a go!len 400hp motor in are cars is only calable of going low 13's.

 

but if they make a stock rebuild.. that does that and this one which should be better i would think this motor should right?

 

Well put! The stock motor is pretty damn good. A little head work, bigger cam, headers and an exhaust system gives mid 350's rwhp and is very reliable.

Keep this in mind: parts cost essentially the same to everyone. Labor will vary somewhat depending on the part of the country, but skilled labor is never cheap and good equipment isn't cheap either. A $3,600 motor is not going to have more than $3,600 in parts and labor minus profit in it. Paying more is no guarantee of getting more, but you are never going to get something for nothing.

Rich

 

I have seen shops rebuild the LT1's with std cast pistons, not the lightweight ones...std chevy valves that are heavier and not backcut like from the factory, they lower the compression not understanding that these motors run great in stock form with high(relatively) compression...it is very easy for a shop to hurt you on power by rebuilding your motor if not done right.