I have been informed that the Jasper stage 3 has had 13 different upgrades for their 305 c.i. engine..

Can anyone tell me what they are and what kind of horsepower a stage 3 engine produces? What makes a stage 3 Jasper so "good"?

Any spec data would be appreciated, all I have been told so far is bigger cams, better springs....and a price of $2400 for it.

Warranty is now 3 years/100K miles I have been told.

I need it to replace current 305 in 91z28.

Thanks!

 

Jasper is a remanufacturing company, nothing more. Any upgrade kit they install will be mild in order to maintain a long warranty

 

From their website:

PERFORMANCE ENGINES & TRANSMISSIONS
JASPER has four levels of engine performance for your project vehicle.

"Stock" is the general production engine offered in a production vehicle.

Stock engines receive JASPER's tried and true methods of remanufacturing, including torque plate honing, three-angle valve seat machining Precision crankshaft machining, oil chamfering and polishing and computer-assisted live-run testing.
The "Class I" engine is the same JASPER general production engine, but with a mild camshaft upgrade. Class I engines generally produce about 10% more horsepower and torque over the standard stock engine.

The next step up is JASPER's "Stock Performance Engine."

These engines utilize a more aggressive camshaft profile compared to the Class I engine. They also receive performance cylinder heads as an upgraded bolt-on part. With performance starting at 300 horsepower, and that fair idle lope street rod & muscle car guys love to hear, the stock performance engine is regarded as the most economical horsepower build.

Finally, the "Class II" engine is for the serious performance minded person who needs power for a specific application. These engines receive additional machining to castings such as align boring... Square decking and balancing of the rotating assembly.
Special components like performance valves, high performance fasteners, a double roller timing set and high tension valve springs are selected and matched to obtain maximum performance for your application. ..

So if "Class II" is so special, why can't they list specs? It "sounds" like something enhanced...Am I gonna get something like 235 HP on it or what (as opposed to 170-215
range)?

 

Provided you don't do a 4" bore mod and you keep the 305 you would be far better off taking it to a local builder. They will give you feedback on what you should be doing to your engine. $2400 for a cam and some valve springs on a stock rebuild is pricey. I was pricing a rebuild out for a 350 with H-beam rods, forged GM crank and forged TRW slugs (cheapie) for ~2K from a local builder here just to give you an idea. A set of hypers reconditioned rods/pistons a good cam shaft and some ARP hardware will go a LONG way with the right valvetrain mods in the top end. What are you looking for power wise out of this engine and do you have supporting mods already?

 

Apparently the Jasper website isn't entirely clear. I discovered that the 305 only comes in 3 flavors...stock, Class I (i.e. slightly modified such that you get a 10% HP increase) or Class II (which a rep. stated increases HP from 80-100 above base stock) Class II requires a different computer chip. All gas engines have been given 13 upgrades from stock. So yes, it is a re=manufacturing company.

Unfortunately my 305 leaked antifreeze into the engine and the place I took it did a "quick fix" by putting some kind of anti-leak fluid in the antifreeze (instead of replacing the head gasket as I was led to believe. When the heads were taken off it was discovered that the original gaskets were still on both heads. (Not the same shop!)

Chemical tests indicate antifreeze in the "oil"; was suspicious when engine threw a code 43 and acted sluggish. It overheated as well.

 

Why don't you just get a 350 and slap your intake manifold on it? Then you're gaining power, keeing it TPI, saving money, and have a good foundation.

 

What I really want to do isn't cost effective. I'd like to mate my 305 with a 5 speed so I have a Z with speed and a little economy. It would be more practical just to buy another Z instead...at least Jasper guarantees its work with a 100K/3 year warranty.

I've had it for 12 years. Darn sentimentality...(but if some1 dropped a new Challenger at my front door...well....)