New cam vs 1.7 ratio rockers

[colin artus]

Jason, it is a well known fact (amongst professional engine tuners) that engines from the USA lose 100 bhp as they cross the Atlantic!

 

[Darrin]

Hi Dave.

The Edelbrock performer RPM package with your carb will make a real 325-340 bhp ish on an engine dyno. I went down the route of importing AFR 165 heads on the back of various US based mustang magazines that showed collosal horsepower from the AFR's. After further upgrading to a 331 stroker package i only achieved 348 bhp on Tim adams engine dyno . Tim really knows his stuff (he builds the engines for genuine 40's cars in the masters series and le mans classic).

The engine had perfect mixture and ignition but showed only a 20bhp gain. I was using the Holley 600, comp cams 280 magnum Roller cam / pertronix electronic ignition and 10:1 forged KB pistons with the 331 crank and rods. Seeing all these dyno plots showing over 400bhp is very surprising and Tim does have a strong view on some of the claims made . He has dynoed hundreds over the years and reckons 350bhp from a 10:1 engine with a fast road cam and a 600cfm carb is pretty good going.

My gut reaction at first blush is that this engine was most likely 10-20% weaker than it could have been had the 185 heads been used with a 750 carb and a bit more cam BUT some of it could also be the difference in the dyno you were using too.

 

[Jason Lycett]

Jason, it is a well known fact (amongst professional engine tuners) that engines from the USA lose 100 bhp as they cross the Atlantic!

i didnt want to say that but that's exactly what my dyno tuner said!!

350bhp is plenty for a road engine in a gt40 anyway !

 

[Doug S.]

350bhp is plenty for a road engine in a gt40 anyway !

That's exactly the advice I've heard from the very first day I began reading this forum!

Cheers!

Doug

 

[Darrin]

That's exactly the advice I've heard from the very first day I began reading this forum!

Cheers!

Doug

I'm wondering if there is a difference in the dynos themselves. Kind of like here in the states where the Mustang dyno always shows a good bit less RWHP than the DynoJet for example. The Superflow shows less than the Mustang even.

Curious to know the brand of the dyno the pulls were made on as I bet this is mostly what is going on. One thing is for sure, we certainly know how to make power from a Ford 302 here. They are as common as can be and a lot of research has been put into making the things produce.

 

[helloyes]

Hi guys i have a Scat 331 stroker kit AFR heads (205) 1.7 rockers and a comp cam running a TWM injection system with a Life racing ecu turning 8000 rpm and it made 498bhp on our dyno (Race Techniques of cheltenhams super flow 902 engine dyno) I think its more a case of matching components correctly, not this dyno or that one or indeed losing power between the US and here although i do agree that this applies to crate engines !
Happy Christmas to all
ps if you type race techniques sbf into you tube there is a video of it running on the engine dyno

 

[Dave Garner]

Just to give a bit of an update.
Newly arrived in the garage is a load of boxes containing a set of Edelbrock RPM Performer heads, Airgap intake, hydraulic roller cam and lifters, 1.6 roller rockers and assorted bits and pieces (sprockets and timing chains etc).
Once New Year is out of the way it is engine out time and then get that lot installed in time for the Spring!
I have the dyno plots from the engine in its current setup, so when it goes back to the (same) rolling road for tuning I will post the results which should give a good indication of the increase.
Dave

 

[marc]

One thing you all did not talk about is giving the additional lift you have to go back and check if your going to tap the top of the piston. clearances may be needed and not to mention geometry of where the top of the valve is being driven. the valve is round and was designed to move for lube and seal performance. the rockers are supposed hit in such a way as this occurs also.