Edelbrock Rpm package

[Clarkson]

Hi guys!
I need some help and advise.
I have southern roadcraft cobra with a standard 350 Goodwrench chevy, BW T5 gearbox and 3.3:1 diff that has done 10K miles.
I am looking to rebuild this engine for more power by fitting an Edelbrock Rpm package and possably 383 stroker kit.
Can anyone please tell me if the stock bottom end is up to the job for 400BHP? If there is anyone out there with this sort of package please speak to me! what is it like? I Hear that the Rpm cam is very radical for road use.Edelbrock claim 410BHP is this a true figure?
I spoke to Real Steel and they claim the best they had is 375BHP.
I am planning to import my parts from the states,I nearly fell off my chair when i saw there prices on the net. About 45% cheaper!!!

Many thanxs!
David Clarkson.

[kdavies3]

Hi David,
I have a 383 stroker fully Edelbrock Performer RPM equipped.
It should be 450 bhp according the "theenginefactory.com" who supplied it, I'm still running it in at the moment but when I lean on the throttle it's awesome.
I have a 3.08 diff. which is quite long legged but the accels are still superb. }(

[graham]

Hi there, Glad to speak to a fellow SR owner, yes they're a bit heavy for a standard tune aren't they. I too have a 350 in mine(tuned) and yep even got the same gearbox BW T5 World Class. Remember if you are tuning the engine the T5 may not be strong enough. Which type do you have? Sorry I cant comment on performance has car not legal and so not driven. Hoping for about 350 -375 hp ish when all sorted (and I still need correct manifolds and sidepipes.) My diff is a 3.54 : 1 so should be interesting. What wheels/tyres have you got? Got any pics?

Regards

Graham

[Ian XII COB]

David,

From what I can see there is a lot of b******t posted about engine bhp. My engine was built in Ozz by a specialist chevy builder who builds engines for hotrods, racers and dragsters. When set up on the dyno it was around the 400 bhp, which he says will probably increase to 410 bhp when loosened up. I was also told that whilst 450 bhp was easily achievable it would prove very untractable below 2000 rpm. I think that American companies such as Edelbrook et al are very optimistic about the power outputs.

Anyone who is used to using dyno will tell you that their are different ways of measuring bhp (e.g. DIN, SAE etc) and they all give very different power measurements, it also depends upon the calibration of the dyno machine itself and the same engine measured on a different machine can often produce quite different power output.

Going for higher bhp with a more narrow power band is not really the way to go as in a Cobra it is the torque that gives you the performance. I went for a flatter torque curve; my engine produces 420 ft lbs peak, but still has 325 ft lbs at 1750 rpm. Even with this set up it is still a little lumpy at idle and below 1500 rpm.

With regard to the strength of the bottom end, if you are going for a 383 stroker then you will be replacing the crank, rods and pistons, so it really depend upon what ones you choose. Some 383 kits are using cast cranks and lower strength conrods, whilst other are forged cranks. I also understand that it is advisable to only do a high power output stroker on a 010 350 block (the one with the 4 bolt mains). I believe that the 2 bolt can fail.

This will probably provoke the usual exchange of exagerated power claims. But its good fun }( }( :*

Ian
XII COB - GD Euro, 383ci, Tremec TKO

[robert]

Definitely go for a 4 bolt.

My unverified HP and torque figures here, verified by Ken Colemans dyno, and very nice it was too.

You will find that the HP figures from some of the US manufacturers are done in an interesting way, WITHOUT any ancilliaries, and they will also take a dozen or so engines, dyno them and use the best figures, hence the marked difference between SAE (US) and DIN (the rest of us). DIN figures are as installed with all ancilliaries, SAE are without ancilliaries etc.


Robert
UK CRC Forum Admin

http://www.cobraclub.com/flags/UK.gif

[wilf]

I have heard people describe the RPM package as "undrivable", but considering the fairly "tame" cam figures, I have never understood why. It will certainly lose some bottom end torque, but in a light car like a Cobra I would personally consider that acceptable.

The only thing I have against it is the lack of a roller follower cam. (although I believe that Edelbrock now do one for the chevy sb, but I havent looked at the specs closely). For a stroker engine, breathing gets even more important, and a proper roller cam gets the valve up off the seat a lot quicker than a flat follower cam. Plus you do not have to break the damm things in. Yes, you have guessed, for engines limited to 6000rpm I am a big fan of roller cams. Above that, not, as the followers are too heavy for proper control of the valve train unless you start to use very heavy spring rates to avoid float.

If you don't believe the difference a good roller cam can make over an equivalent duration flat follower cam, try playing around on desktop dyno.
"Bench racers" also hold that you can get away with a longer duration cam with more overlap (smaller lobe separation)by going the roller route, whilst maintaining good idle and bottom end torque.

Just some thoughts.

[Clarkson]

Hi Ian,

Whats the spec of your engine?

David Clarkson.

[Ian XII COB]

Hi David,

My engine was built to a spec recommended by the engine builder rather then an of the shelf bolt on kit. I don't have the details with me at present so will do it from memory:

Block - Chevy 010 casting, 4 bolt mains
Crank - Eagle 383 stroker
Rods - Eagle H Beam
Pistons - need to check
Cylinder heads - RacerPro Aluminium 192cc (An Australian product)with extra flowing by Walkom Performance
Camshaft - Crane, need to check which one I ended up with as three were tested during development, one gave over 450 bhp but had nothing lower down and was too extreme. I ended up with the middle one of the three but cannot remember the timing.
Rockers - Crane 1.6:1 Roller Rockers
Bearings - need to check
Fixings - ARP high tensile
Harmonic Damper - need to check
Ancil Drive - Al spline pulleys with 1.5 inch flat belt
Clutch - Twin plate with hydraulic release bearing, i.e. no clutch release arm.
Starter Motor - Small high torque
Inlet Manifold & Carb - Holley 650 4 barrel with a Victor Junior manifold.
The whole of the engine is fully ballanced and designed to handle much higher power output then I currently have, in then interests of reliability.

There some pictures of my car in the gallary, I have some of the engine that I will scan and post.

Ian
XII COB - GD Euro, 383ci, Tremec TKO

[RigMan]

HYdraulic Thow out bearing?............AHHHHHHHHHHhhhhhhhhhhhhhhhhhh!


RigMan

[Clarkson]

Hi guys,

I think I have to agree with Rigman.I have one in my T5 box with never ending problems!!

No room for anything else.

D Clarkson