Bike Carbs Or Throttle Bodies

[Guest ollie chapman]

I spoke to Robin Hood the other day. One of the chaps (not Richard) reckoned that ultimate performance would be reached on a 2.0 zetec by using throttle bodies rather than the bike carbs that I currently have on.

 

Obviously Jenvey throttle bodies etc are seriously expensive £1515 + but I wondered if you could use a bike injection system such as the one on a GSXR 1000.

 

Would these be able to be mapped in to a 3D megajolt ignition and if so would the provide much more performance than the current bike carbs?

 

An interesting thought... Can anyone help?

 

Thanks!

[Mitch]

you can use bike throttle bodies, but would need to change jolt to a squirt version whicj would power both spark and fuel,

HTH

Mitch

[Guest gdc]

i would if i could afford go the t/boddy route, the bike carbs are ok as on dans lightweight but can be a bit temprementle yes my spelling sucks . they suffer from over fueling and in the hot wheather the carb bowls get so hot under the bonnett the fuel vaporises we are concidering changing his to injection , because of this prob ,

please note the prob might not be as bad in a 2b with a larger area under the bonnett .and better cooling .

graham

[speedtripledan]

my bike carbs don,t suffer any problems on my 2B but i do force air around them etc

[Guest ollie chapman]

Does anyone think it it is actually worth doing? What would the BHP increase be when plumbed in correctly?

 

Thanks.

[Guest rob11]

Hi,

 

Might be totally wrong but Richard thinks (he knows someone who has done it with same engine RS2000 16v) I should be getting approx another 30ish BHP when mines up and running. Going to be using GSXR 1000 throttle bodies with Emerald ecu.

So should be putting out about the 180BHP from my rs2000 16v.

Would have thought something similar with the zetec.

HTH

 

Rob

[Guest scottie686]

Not sure if this is a good alternative, buth thought i would share! I'm currently running ZX9R carbs on my standard 2.0l silvertop and the last dyno run gave me an output reading of 138bhp. I was hoping for more. Having said that, my Zero doesn't hang around but after a recent track day have decided this winter to take it off the road, give the engine a bottom end rebuild and recon the diff and g'box and look at increasing the power to 200+bhp.

 

Whilst researching the possibility of changing to throttle bodies and the potential power gains for my budget i gave Paul a call at Dunnell Engines who supplied my current shortened sump and lightened/balanced flywheel. Dunnells have various options/packages for both Zetec and Duratec applications and he highlighted one that might suit both my budget and my requested power output. He called it 'Option 3'. The kit consisted of;

 

- Inlet Manifold - Fettled, Carburettor mounting kit

- 3D Clubmans Ignition Management System (IMS) + manuals

- Wiring Loom

- Inlet manifold gasket

- 2x Dunnell ZRV camshafts retaining standard hydraulic tappets

- Modified cylinder head (RMP 101)

- 16x Competition high lift valve springs

- 2x Vernier camshaft pulleys

- Set of heavy duty connecting rod bolts

 

This kit excluding the Brand New Twin 45 DCOE's is £2,250 plus VAT or £2,890 plus VAT including the Twin 45's. They claim with the map they provide and with these components they are seeing reliable results in the region of about 220-237bhp! For me, the cost of TB's which will be £1,500-£2,000 with a decent stand alone management seemed alot to increase to around 190bhp and to then buy cams or a modified head to increase further would just blow the budget sky high, but not to mention the added work and hidden costs to go from carbs to injection i.e. running an extra fuel line, fitting the additional sensors.

 

Hope this is of some interest.

 

Scott.

[Longboarder]

An engine is just an air pump. Any given engine including yours Ollie has a certain efficiency/maximum through put of air. Add the right amount of fuel to this and you will get max horses. If your carbs are fuelling OK at 6000 rpm then changing to throttle bodies and having them fuelling OK at 6000 rpm will not give you anything. No extra horses. No extra torque. Just exactly the same as before.

Carbs are relatively crude things and it's difficult to get them to give the right fuelling over all throttle openings and revs. Switching to mapped injection through throttle-bodies allows you to get fuelling near right at all revs and throttle openings. Ditto ignition. So it will be much more drivable, fuel efficient, safe etc and in some parts of the rev range where fuelling on carbs was too rich or too lean you will have more power.

In practice most people set up their carbs to be about right at the top end and endure the coughing and farting at part throttle. With bike carbs you can do better than that with needle and jet changes.

If you are thinking of spending cash do it on a rolling road session and get your present set-up right. That will release all the power in your engine. Switching to throttle-bodies will get you no more unless you increase its efficiency as an air pump. That means head work, porting, bigger valves, raised CR, aggressive cam, blower or turbo etc.

To genuinely get more power you need 1. MORE AIR and 2. THE RIGHT AMOUNT OF FUEL IN THAT AIR. If you don't have more air how can you get more power. If you don't have the right fuelling you are not releasing all the power your engine is already capable of.

If you get an extra 30bhp at the top end by switching from carbs to injection your carbs were set up very badly!

 

Nigel

[Guest ollie chapman]

Sorry for the late reply, but I have been away. Thanks for the info guys, it is all very interesting. After reading your interesting post Nigel I think it would be best to stick with the bike carbs.

 

Your set up from Dunnells Scott sounds really sweet, I'm surprised that your bhp was so low, do you think that this could because your running a silver top instead of a black top?

 

Cheers

[speedtripledan]

The figure of 138bhp on the zetec sounds a little dissappointing i was thinking of using a zetec in the future but if that is all the power it can produce on carbs it does not seem worth it baring in mind my pinto is only 14bhp down on that at the moment..

[Guest Ecosse]

Hey guys, I'll just throw my 2p in here.

 

Having had both TB's and Bike Carbs on a zetec, I can definately say that the TB's were FAR better, although, alot more expensive.

 

I ran the Weber Alpha Gold Kit (TB's, ECU etc EVERYTHING, and I do mean everything, that you need to fit it) which is already mapped and ready to go straight off.

 

That along with WA's Platinum Kit (cams and remapped ECU) on my old 1.8 Zetec (in my Mk2 Fiesta XR2) put out 176bhp & 128lb/ft. Idled perfectly, revved fast and freely, gave 27mpg wheter pootling around to being thrashed. (TBH, really REALLY wish I'd never sold that setup now)

 

The bike carb setup I ran on another XR2 with a zetec (2.0 this time) with R1 carbs. 130-140bhp at most, far hungrier for fuel and just not half as nice to drive as the TB setup.

[Knock-on]

Like most things, it's not the size of the wave but the motion of the Ocean.

 

Properly set up, there may be 10 BHP difference between a 2.0 Zetec (or 1.8 running 2.0 Cam) running carbs or TB's.

 

You should expect 160 - 180 depending on the engine and configuration set up.

 

Nigel is 100% correct. If you haven't got the air and petrol going in in the right mixture and rate, if you can't burn it fast enough and if you cant GET IT OUT then you can throw silly money for no gain.

 

Spend some time on a rolling road but make sure you've got a nice flow of gasses out first or you're doomed.

 

I'm running a 2.0 on ZX9 carbs with Mega Jolt and would not be too impressed with 138. The engine was that to start with