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Is 250bhp on carbs possible?

769 views 14 replies 7 participants last post by  rgv_stu 
#1 ·
there was a 2l 16v astra at Knockhill (white one last track day f-reg) and it was well fast, I mean modded cossie fast. Anyway my mate talked to someone that knew the guy that has the car and they reckoned it had 250bhp (beliveable with the speed of it) on carbs (?) I thought that sort of power would only be available with a well tuned tb setup. So what would be needed with carbs for that sort of power?
 
#2 ·
It is possible, but highly unlikely. To get that sort of power with carbs you would need to spend "race car teams" amounts of money. It would be far cheaper to get that power using TBs. I'd say 210 - 225bhp would be a likely estimate for a very modd'ed 20XE on carbs
 
#3 ·
carbs will flow just as much air (except when changing to roller throttles and 300bhp outputs) so no reason why they shouldn't be able to make just as much power.

but the thing with them is that achieving good fuelling right across the rev range is much harder - and the engine will be peaky and a bit lifeless off cam - whereas with throttle bodies you can at least optimise everything, everywhere, and have a bit of driveability out of the power band.

250bhp on carbs and having a tractable engine is quite an acheivement, considering the cams needed for that sort of power - must've been a very well setup engine indeed.
 
#5 ·
i thought that tbs were better at flow and hence power because tbs dont have the venturi / choke :confused:

u can obviously get a larger carb but u need to speed the air up past the main jet to get the suction of fuel, so restriction is still there unlike using an injector:confused:
 
#6 ·
It's perfectly possible to get 250BHP from carbs and it doesnt have to cost a fortune, however getting the fuel slope right everwhere isnt easy. The advantage with TBs is two fold, firstly accurate fuel metering, secondly lower drag through the throttle body than through a carburettor, a venturi is designed to create drag and hence give a 'signal' to the jet orifice in the auxilliary venturi, in a TB there is no Aux vent and no venturi, just the throttle plate, in a barrel TB as stated there is no throttle plate, but at part and low throttle the drag and air distribution is *interesting*..

Dave
 
#12 ·
It makes sense I figured from the name that the throttle barrel would rotate rather than a flap in the middle but I just thought I would check.

Cheers
 
#15 ·
u may recall a few months ago i asked opinions about using motorbike carbs on a car

does anyone make a flatslide carb for car applications????

the thing i was thinking was because of the way in which it opens the airspeed is kept high /drag as mr andrews said right next to the main jet /needle. because of this there is no restrction (ie choke ) in the carb barrel or butterfly in the way.
u can buy these flatslide carbs to replace butterfly factory fit style ones and give the bike much better responce / performance etc

opinions please ....
 
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