Would the new GM 290 HP crate motor be a good combo w / the Weiand 142 blower? The compression is a blower friendly 8.5. The heads are'nt the best and I'm not to sure how friendly the cam would be? Has anyone run this combination? TX.

 

Anyone?

 

I plugged the 290 Gm motor into Engine Analyzer and added a 142 blower it says it gained ~60hp/tq I don’t think 60hp is worth the $1500 price tag on that blower.

 

Ouch! Not alot of bang for the buck. Should'nt one be able to get about a 30% to 40% increase in HP and Tq. with that blower?

 

If I was going to do this, I would change out the cam to maximize the potential of the motor. I would say, with the proper carb, cam, valvesprings, 400 hp isnt hard to achive. The 142 is a small blower. If you wanted 500 hp then the 177 is a better pick. Dont forget that ,even though 400 hp seems low for a supercharged motor, This would be 400 hp @ 5000-5500 rpm and alot of low end torque. A normally aspirated 350 cid motor would have a hard time to achive that.

 

The GM "290hp" crate motor comes with the old L-46 L82
cam from the 60's.. If you were to advance it in the motor about 7degrees it would be more "blower friendly"

But a simple switch to a crane off the shelf grind cam would really sweeten it up. The crane pn is 113801. There are other blower friendly cams for sure but this one is a sweet street cam for a street B&M/ holley 142 blower/350 project . The advance is already built into this grind.

If you were to pull the heads and home port them and swap the cam you'd have a winner.

I believe this motor comes assembled with a thin factory steel shim gasket. Replaceing this gasket with a thicker felpro gasket would further lower the cr allowing more boost.
More boost= more torque and power.

if while porting the heads you were to also deshroud (grind) the chambers each to the tune of 4 cc's along with a .051" thick
felpro head gasket your cr should be 7.6:1
Should be able to run 10psi boost @ 7.6:1 compression on preminum gas.

if you were to build this motor as I describe it would make 450hp, very near 500ftlbs torque at 10psi boost using 92- 94 octane fuel.
it will be a tame 450hp too. easy daily driver.

Sell off the cam that came in the motor with the lifters on ebay to someone that wants it. It's an old 60's era muscle car/vette grind, it will sell. You'll offset most of the cost of the Crane # 113801 cam+lifter set and be miles ahead.

GM recommends using Ac delco R45TS plugs and 34degrees total timing. For your blower motor you'll want cooler AC R42T ( not TS) or Champion RV8C plugs and 26 to 30degrees total timing. under boost.
Modify the distributor to limit the mechanical advance travel so that you end up with 16 initial at idle (700rpm) and 28 total at 3500rpm.
Get a adjustable vacuum advance ( Crane) and fine tune it. plug the vacuum advance into manifold vacuum under the blower. not on the carb. You want 0 deg vacuum advance when the motor is under boost. and about 10 to 15degrees while at high manifold vacuum (light cruise)

can you post a picture of the heads you have? Want to see detail near the spark plugs on the heads. (light weight or heavy duty casting version )

 

I have thought about what a little 142/144 blower would be like on that motor. I suspect that +60 HP is maybe a smidge on the conservative side for 6PSI. 100 HP might be stretching it, but not outside the realm of possibility.

Like was mentioned above the torque increases from the roots blower would make that motor feel like nothing you've ever experienced with a N/A combo of similar horsepower. In short, it'll run like a raped ape and you'll never need to take it over 5500 to go fast, either. No high stall converters or steep rear gears necessary.

 

This is from the Goodwrench build up series in Chevy Hi Performance, the eng was the base LM1 but I assume the same heads are used on the 290 justing stabbing in a bigger cam



They ended up putting a 142 blower on LM1 with Trick Flow heads to get 471 hp and 452 lb-ft of torq.


jbv, if you do go this route buy the base LM1 to save some $.

 

they should have tryed 1.6 rr
i'd bet $$ they would gane 20 to 30 hp on that combo