375 hp 350? [Archive] - Chevelle Tech

: 375 hp 350?

Jan 20th, 03, 10:43 PM
What does it take? I am looking at buying a car, 78 or so Trans Am, the guy swears it has a 375hp "crate motor" 350. I said BS but thought I should ask somebody with more brains than myself. It has an edelbrock intake and carter carb, other than that I can't tell you anything other than the heads are removed because one of them cracked. My understanding is that you have to do it right to get 375 hp from a 350, but I am still just learning.

Jan 20th, 03, 11:19 PM
Find out what company built the crate motor and simply call or look up their web site.

It is not difficult to get a "350" to 375 HP. Some clues wild be the heads and valve train as that would be the best clue to how powerful the motor was built.

I want to die in my sleep like my grandfather...

68 Corvette - 383 CI 427 HP
69 SS Chevelle being updated to Pro-Touring
97 Z-28, less than 15,000 miles on it!

Not screaming and yelling like the passengers in his car.

Jan 20th, 03, 11:28 PM
the Fast Burn 385 350ci sbc GMP crate engine made well over 400 hp on the dyno, and its rated at 385 hp. It doesn't take much to make a high horsepower 350. The biggest issue is a set of good heads, and the right cam.

Jan 20th, 03, 11:46 PM
As stated, it is not hard to get 375hp from a 350. Chevrolet has even done it with production engines in production cars.

In 64-5, the 327 was available in a 375hp version. It was the fuel injected 327 which was available in Corvettes. Then, in 1970, the LT-1 350 in a Corvette was rated at 370hp. The 70 LT1 and Z-28 engines were EXACTLY the same engine. The LT1 in the Corvette was rated at 370hp and the Z-28 was rated at 360hp. Even though the two engines were the same, but had a 10hp difference, the reason for the difference was because the Corvette had an exhaust which had less back pressure and that was the reason for 10 more hp in the Vette. If you did absolutely nothing whatsoever but add headers to these engines and a VERY efficient 2 1/2 or 3in exhaust system, that would boost it some. These engines had solid lifter cams.
Also, BOTH the 327 (65-68) and 350 (69-70) were also available in 350 hp versions, which had hyd cams. Again, adding only headers will boost the output of these engines also.
My whole point here is that if Chevy did it with production engines (which are ALWAYS built a little on the conservative side so they will last through the warranty period----ya, right!), then it is quite easy for a home built version to top 375hp.

Tom Parsons

Big Block Dave
Jan 21st, 03, 7:36 PM
Anytime anyone tells you a horsepower figure, whether they are trying to sell you or impress you, DONT BELEIVE THEM, unless they have a dyno sheet.

People throw around horsepower figures so much its disgusting, and it does nothing other than make me close my ears, and stop paying attention to the conversation.

Dont rely on him for HP numbers.....push him for receipts of parts that are in the motor, and assess for yourself what the car is capable of.

Pat Kelley
Jan 21st, 03, 9:55 PM
Time slips are nice.

plain 69
Jan 21st, 03, 11:22 PM
All these engines that DZ brought up had at least 11.00 to 1 compression as well. With at least a 780 Holley that was installed on the LT-1. The L-46 350 350's of 69-70 had 11.00 to 1 compression but had Q-jet carbs I think with a Hydraulic camshaft. A lot of people forgot about that paticular camshaft it was .460 .480 lift. They even used that camshaft in the L-82's from 1973-1981 as well.

Certainly a lot of 350hp or more small blocks. They had a common denominator though.

2.02 1.60 Cylinder heads
11.00 to 1 compression
Solid Lifter camshafts
780 Holleys or Fuel Injection
Decent aluminum intakes

A 350 with these items will probably make 350hp or more depending on the state of tune.

69 Malibu 406 3680lbs Turbo 350 2400 stall, 3.73,XE274, Performer RPM Q-JET, 800 Q-JET, Sportsman2 64cc 11TO1 12.65@105.5 mph on Drag Radials

ACES Member #3635
Tri-State Chevelle Member# TSC-010
Larry G.

Jan 21st, 03, 11:50 PM
The 370 hp 70 LT-1 had 11:1 CR, and the 71 LT-1 had 9:1 CR and 330 hp according to a booklet I have. I've read elsewhere that the 40 hp drop was due to the CR decrease, but this gives different head #'s, 186 or 414 for the 70, 487 heads for the 71.

A lot of figures in this book don't seem to jive, and I can't say if the head casting numbers are accurate. It also lists a 182 cam, but everything else I've read lists a 178 cam for the LT-1. I think Crane's Blueprint version is called a 182, but I'm not sure.