i was wondering how much power can one get out of a 4.9? im rebuilding one for my 92 eldorado and i want more power, im hopin to get 300 hp or more out of the motor, and then possibly intallin a twin turbo set up, 10 psi, intercooler... goin for 450 hp, can you build the tranny to handle this kind of hp?

 

No expert here but current Northstars put out 300 hp and as the owner of a Deville I can tell you this is enough to standoff most muscle cars from back in the day. Hard to believe but it's true, so 300 in your Eldo should be just fine. I don't see any reason why that 4.9 can't get there. My hobby car is a 73 Pontiac so I know Pontiac guys that have put built Chevy small blocks, like 400 hp,on late model Bonneville tranmissions in Fieros and they stand up well with little to no work so there you go on the tranny.

As far as prfomance goes you should pick up25 or so HP with a good free flow dual exhaust, a good cool air intake would help by up to 15 HP, and then there is your sparks, wires and coils. This is all easy HP and that combo there is good for at least 50 HP.

 

I was talking with afriend and he said to mention throttle body spacers, a machined piece of aluminum which raises the drop of the air fuel mixture into the intake and helps cool the charge as well. Another thing he said was to go get a Chevy 454 throttle body which is bigger and jet it for a 350 and put it on. Also you can consider a new chip, which are advertised to bring up HP up to 30 ponies.

 

does anyone know if over sized valves areavalable? and if i were to coat the top of the pistons and combustion chamber with that high temp coating that drops cylinder temp how much boost and compression do you think i could squeeze out it on 91 oct? im thinkin 10-1 with 9 lbs of boost and an intercooler would be possible?

 

Imo you are looking for trouble with that turbo idea. Cadillacs are what they are. If you want big horsepower go to a small block. Everybody and his uncle makes parts for that. Better still go to GM and get a crate motor.

 

The northstar is a high compression motor, twin turboing it would take alot of work and take up alot of space. I've heard full exhaust, and retuning the computer makes close to 400. but the motor is mostly aliminum, so once it overheats, its shot. I wouldnt put that much power into a FWD drive car anyway. I havent heard of much of an aftermarket for the transmission for the northstar, letalone the rest of the car.

 

Downwardspiral, The 1991 thru 1995 4.9 liter engine used in Eldorado, Seville, DeVille and Fleetwood lines is an overhead valve, 90 degree V8. It has an aluminum block and intake with iron heads. There are two configurations, PFI engines have larger throttle bores, as well as bigger ports and valves than previous TBI engines. The '90 - '95 engines are equipped with a sequential Port Fuel Injection (PFI) system. The Sequential Port Fuel Injection system replaces the Throttle Body Injection (TBI) system used in previous years. The PFI system replaces the two injectors in the throttle body with eight injectors located in the intake manifold. There is one injector above each intake valve. In any case it is not a Northstar.

 

Forgot about that, the northstar is 4.6 anyway, isnt it?

 

The Northstar has been made in a few displacement but currently sits at 4.6 litres. There is a 4.0 litre version that went in Oldsmobiles. The 4.6 has two configurations,L37 and LD8. The difference is in the cams. The LD8 produces less HP but more torque in a lower RPM range than the L37. The LD8 is therefore a better engine for quick aceleration and throttle response but because Horsepower sells and not Torque the L37's with 300 HP go into the "sport" models. My Deville is the LD8 with 275 HP and 300 ft/lb torque and the salesmen at the dealer tell me it feels quicker in town than the L37 Sevilles with 300 HP.and 295 ft/lb torque.

Even the sales brochure for the Deville bares this out. It shows the Devilles with 275 HP and 3.11 axles doing 0-60 in 7.8 seconds while the 300 HP models get a muscle car huge 3.71 axle ratioand only get a 0-60 time of 7.6. With the same axle ratio the less HP car would definitely be quicker. As it is they are pretty much the same.

 

Imo i would not turbo charge your 4.9 if you are trying to get 10 to 1 compression. especially if you want to run with 10psi. this will basically ruin every thing you did. if you want to turbo charge an engine you want to use a lower compresion ratio the best compression for turbo charging ranges from 7.0-8.5 to 1 this will allow for more boost if nececary so if you had 8.5 to 1 with 15psi you would be better off also your engine would last longer. My deville with the same engine and i just want to get a 75 shot of nitrous just becase its a cheap.