Thinking of Different Combo Advice

[bedjo78]

I have used 1-3/4" merged header but seem to be lost of hi rpm power 7000-8000rpm

Hi All..

Right Now I have two sets of Engines here are the Spec that for Cirduit racing Capacity max 2100CC

1. 80X90.5, webcam 121/125, 1.25 ratio rocker, 5.5 H beam, Head CNC Ultra Mag Plus CB044 42X37 with matched manifold. Weber IDA with 40 ventury. merged 1-7/8"

2. 80X90.5, FK8 ratio rocker 1.5 . 5.5 H Beam, Steve Tims Stage2 043head 42X37 with matched ported manifold. DRLA 48. merged sidewinder 1-3/4"

Right now i'm thinking of building same capacity but with different combo as follow

74X94. CNC WedgePort 044 42X37, webcam 121/125, 1.25 ratio rocker. 5.5 H Beam, IDA48 with 40 vent, merged 1-7/8

Question...Is the 74X94 will be perform better than 80X90.5? engine will rev up to 8000rpm sometime 8500++ in Circuit racing

[kingsburgphil]

Can you describe "Circuit Racing"? 

[bedjo78]

Can you describe "Circuit Racing"? 

Circuit  Racing is 12 laps Racing on 5 km long Race Circuit just like Touring Car championship or A1 or F1  racing

We have retro Race up to 2100CC and also One Make race VW

[lowfastbus]

I have a 74*94mm engine with FK10 and CNC wedgeports, IDA's...
Power up to 7500rpm then it drops, can't imagine doing 7500rpm more than 20seconds in a time.

How do these engines keep up?
How often do you rebuild them?

Greets,
Jelle

[bedjo78]

I have a 74*94mm engine with FK10 and CNC wedgeports, IDA's...
Power up to 7500rpm then it drops, can't imagine doing 7500rpm more than 20seconds in a time.

How do these engines keep up?
How often do you rebuild them?

Greets,
Jelle

we shuffle pin the block, balance the parts, lighten flywheel, balancer pulley, PSI spring with Titanium retainer, filter and oil coolers (we spray the oli cooler with cooled ice water as well). and the engine and carbs was cooled by air that was passing the dry ice chamber . The engine rpm range 4000-8000rpm often more if side by side. NO ENGINE BRAKE for sure otherwise we lost the Engine in short time

we should usually rebuilt the Engine in one season (5 races) otherwise if something broke...