Engine spec cock up!

[runningmonkey]

I feel I may have ruined my engine by installing a different/wrong cam

Long story short, my engine need re building and I thought as its in bits lets up the cam, more power right  now the engine builder is a great guy & vw engine builder but know little about drag racing so couldn't give me any advice on what was the best spec so just went ahead with my instruction

Now Iv got the engine back and ran it in again, but this time the new engine feels a lot slower and with less poke then my old one, even so Iv gone bigger on the cam (Engle FK10 to Engle FK87) I was expecting more performance

engine spec as follows

2180cc

82mm bugpack crank
92mm Barrel & pistons
pauter rods
CB performace super race rods
ARAO stage 3 heads with 42x37.5 valves
Engle FK87 Cam (changed from FK10)
1.4.1 ratio rockers duel spring
Weber 48's
009 with petronix ignitor kit + flame thrower coil
Lighten flywheel
Blue printed bottom end


Is there a chance that installing the new cam has messed up the overall spec or compression ratio of the engine?

[richie]

if the heads were maxed out with the k10 then going to the 87 wont see any gain,also it will want to make power higher making it less drivable in everyday use.
Did you run it at the track yet? what gearbox ratios does it have?
You need to give some info,what is the compression ratio,did you change venturis and jetting in the idas,what size exhaust,what fuel as well,that would help to give a better answer

cheers richie

[Greg G]

I like running a minimum of 10:1 compression with a FK-87. You will need close ratio gears for it work on the track also.

Greg

[Zach Gomulka]

I'm not sure if running two sets of rods is beneficial

Like the others were saying, I think CR is crucial with that cam.

[runningmonkey]

if the heads were maxed out with the k10 then going to the 87 wont see any gain,also it will want to make power higher making it less drivable in everyday use.
Did you run it at the track yet? what gearbox ratios does it have?
You need to give some info,what is the compression ratio,did you change venturis and jetting in the idas,what size exhaust,what fuel as well,that would help to give a better answer

cheers richie

Not really sure on the CR when the engine was first made by russ arao in the states it had a CR of 9.4:1 and was built to run on 91 octane gas, (what ever the uk equivalent is am not sure)  The engine has been rebuilt twice seen then (both times for big end bearing) and as I said the cam has been changed but every thing else is the same as when he made it, I run it on normal UK fuel which i think is 95 octane. gearbox is Rancho pro street swing axle with Superdiff. Heavy duty, aluminium side plate, Welded 3rd and 4th gear hubs, Hardened keys, Steel shift forks. exhaust is 4 into 1 1” 1/2” Hi performance exhaust, I believe the jet are 170 but am not 100% sure on that

[richie]

ok,well for me thats not enough compression for that cam,also that header is much to small,its proberly restricting or choking the engine,with the stock gear ratios it will be a pig   Do you know if the heads were freshened up dring the 2 engine rebuilds?If not then the valve springs would proberly need changing and all the seats and valves re cutting or at least a valve job.
Also I would be running it on the best available fuel and if the jetting wasnt changed after a cam swap then it proberly needs doing as well.

The 1st thing i would change is the header though,and then figure out the jetting

cheers richie

[dragvw2180]

 I agree with Richie on almost everything . I have built several engines for friends who were going to convert over to turbo when their budget allowed and set the compression at 8.2 and with proper tuning they ran very well with the FK 87. Is it the best choice, no  , Is it fun , yep.  Like Richie said try a bigger exhaust. Mike McCarthy