427 How much HP?
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
427 How much HP?
Hi,
I have just bought a 427 for my vette
Previous owner said it was making 450hp, does this seem right ??
3963512 block, 30 over with TRW's 50cc domes
Isky Z33 solid (250 dur@ .050, .540 lift)
Gm oval port 3931063 100cc closed chambers
weiand single plane, 850 D/P
Cheers
I have just bought a 427 for my vette
Previous owner said it was making 450hp, does this seem right ??
3963512 block, 30 over with TRW's 50cc domes
Isky Z33 solid (250 dur@ .050, .540 lift)
Gm oval port 3931063 100cc closed chambers
weiand single plane, 850 D/P
Cheers
Le Mans Master
Joined: Dec 2006
Posts: 5,557
Likes: 9
From: Oquirrh Mountains
St. Jude Donor '09
If those specs are correct 
then the engine has at least 14:1 compression ratio. I don't recall a 50cc 427 TRW piston for use with closed chambered heads, but I don't completely trust my memory anymore these days. Way too much compression for a street engine if that's what your intended use is.
With the specs you listed though; I agree it would be in the 450 hp ball park.
then the engine has at least 14:1 compression ratio. I don't recall a 50cc 427 TRW piston for use with closed chambered heads, but I don't completely trust my memory anymore these days. Way too much compression for a street engine if that's what your intended use is.With the specs you listed though; I agree it would be in the 450 hp ball park.
Melting Slicks
Joined: Oct 2008
Posts: 2,154
Likes: 69
From: Regina Sk Canada
Just looked up the Trw piston, and the one i found listed that has a 50cc .585 dome is for an open chamber head with 116cc chamber thats 11.66-1 compression. So a closed chamber head isnt going to work with that piston.
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
If those specs are correct then the engine has at least 14:1 compression ratio. I don't recall a 50cc 427 TRW piston for use with closed chambered heads, but I don't completely trust my memory anymore these days. Way too much compression for a street engine if that's what your intended use is.
With the specs you listed though; I agree it would be in the 450 hp ball park.
then the engine has at least 14:1 compression ratio. I don't recall a 50cc 427 TRW piston for use with closed chambered heads, but I don't completely trust my memory anymore these days. Way too much compression for a street engine if that's what your intended use is.With the specs you listed though; I agree it would be in the 450 hp ball park.
I have not opened it up to verify, rather second hand info.
Also been told its run 10's in a light car.....
What then would would you guess whe domes are likely to be ?
Trying to figure some new heads to put it in the early 11's compression wise
Thanks
Le Mans Master
Joined: Sep 2000
Posts: 9,078
Likes: 7
From: DFW TX
Cruise-In VII Veteran
St. Jude Donor '07
Seat of the pants feel? 450hp should scare the crap out of someone that is not use to driving a C3. How about taking us for a ride in the car via Youtube? Maybe the wifey can do the video'ing, we always like to hear them scream.
BTW - A 327 can run 10's in a light car.
BTW - A 327 can run 10's in a light car.
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
I have a option to buy some 3946074 casting,think they are 110 chambers ? guy wants good $$ for them, for the same $ could get some new GM heads... hear there are issues with these old alloy heads.. like to keep the compression up, race gas is not much more expensive that pump gas over here, smiles per gallon and the sweet perfume
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Team Owner
Joined: Oct 2004
Posts: 81,241
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From: altered state
St. Jude Donor '05
Old GM alloys? shoot just get some good aftermarkets and really step up your power game. let the untouchable stuff sit and collect dust somewhere.
tpi421Vette in the C4 tech section can do you a screaming deal on a set of AFRs. Sell your oval ports to offset cost, lighten the front end up build more power and worry less about running compression.
tpi421Vette in the C4 tech section can do you a screaming deal on a set of AFRs. Sell your oval ports to offset cost, lighten the front end up build more power and worry less about running compression.
Le Mans Master
Joined: Sep 2000
Posts: 9,078
Likes: 7
From: DFW TX
Cruise-In VII Veteran
St. Jude Donor '07
Le Mans Master
Joined: Dec 2006
Posts: 5,557
Likes: 9
From: Oquirrh Mountains
St. Jude Donor '09
Yes I agree it seems unlikely that compression is that high, Its always been run on race gas.
I have not opened it up to verify, rather second hand info.
Also been told its run 10's in a light car.....
What then would would you guess whe domes are likely to be ?
Trying to figure some new heads to put it in the early 11's compression wise
Thanks
I have not opened it up to verify, rather second hand info.
Also been told its run 10's in a light car.....
What then would would you guess whe domes are likely to be ?
Trying to figure some new heads to put it in the early 11's compression wise
Thanks
A friend had a similar engine in a 68 camaro in the late 80's and it did run tens. I would be tempted to run it as is and see how it does.
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
Nope, all good idea's, wife in vette, unlikely to happen, roads here some what average due to 2 major earth quakes in recent times, engine still on engine stand, will take some video once is installed, 450hp is nice but after having had more hard to go back, 500hp this old girl would be nice......perhaps some AFR's are the plan
Melting Slicks
Joined: Oct 2008
Posts: 2,154
Likes: 69
From: Regina Sk Canada
Just thought i would give you this bit of info. i built a 427 several years ago, and spun it on the dyno. The build goes like this.
427 + .060= 440
11.25-1 compression
Eddy rpm performer heads
oval port 122 cc chamber
.585 lift .245/.255 @.050 on 112LSA
Hydraulic roller
Holley Strip dominator intake
850 Dbl pumper carb.
34 degrees total timing.
550 hp and 513 tq.
Premium pump gas motor had good manors and drove nice on the street.
427 + .060= 440
11.25-1 compression
Eddy rpm performer heads
oval port 122 cc chamber
.585 lift .245/.255 @.050 on 112LSA
Hydraulic roller
Holley Strip dominator intake
850 Dbl pumper carb.
34 degrees total timing.
550 hp and 513 tq.
Premium pump gas motor had good manors and drove nice on the street.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
.A BIG Chevy and hes looking for more HP.....The only thing I exclude from the street are my race cars that don't have radiators. So 'almost anything goes including single digit 1/4 mile pieces street driven.....all it takes is money and brass *****........
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
Just thought i would give you this bit of info. i built a 427 several years ago, and spun it on the dyno. The build goes like this.
427 + .060= 440
11.25-1 compression
Eddy rpm performer heads
oval port 122 cc chamber
.585 lift .245/.255 @.050 on 112LSA
Hydraulic roller
Holley Strip dominator intake
850 Dbl pumper carb.
34 degrees total timing.
550 hp and 513 tq.
Premium pump gas motor had good manors and drove nice on the street.
427 + .060= 440
11.25-1 compression
Eddy rpm performer heads
oval port 122 cc chamber
.585 lift .245/.255 @.050 on 112LSA
Hydraulic roller
Holley Strip dominator intake
850 Dbl pumper carb.
34 degrees total timing.
550 hp and 513 tq.
Premium pump gas motor had good manors and drove nice on the street.
Le Mans Master
Joined: Sep 2000
Posts: 9,078
Likes: 7
From: DFW TX
Cruise-In VII Veteran
St. Jude Donor '07
Nope, all good idea's, wife in vette, unlikely to happen, roads here some what average due to 2 major earth quakes in recent times, engine still on engine stand, will take some video once is installed, 450hp is nice but after having had more hard to go back, 500hp this old girl would be nice......perhaps some AFR's are the plan
Pull those heads and take a look.
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
