Bike Throttle Bodies

[Guest P Zero]

I know this has been touched on a lot, but there seems to be little information on the results of such a conversion. Does anyone know what realistic power gains would be from using bike throttle bodies on an Mi16 motor, specifically the XU10J4? Torque, BHP, etc.

 

I'd love to go the jenvey route, but at about £1500 it's quite expensive. I've heard of people completing a bike body conversion for around £500.

[28CRAIG 2]

It all depends on how well the manifold is made and linkage ect.

 

Have a look at dream weaver rebuild topic he has managed the same gains as you would expect from jenvey's

[Dream Weaver 2]

You can do them for less than £400 if you're lucky with some eBay finds. Mine cost nearer the £500 but that included buying 2 coilpacks and some other extras.

 

My engine was 180bhp before the bodies with the headwork and cams, and made another 19bhp after the bodies, although the engine was in different cars and on different rollers for those 2 figures. The 199 figure was done on a very acurate RR though where the Std Impreza's on the day were making Std OEM figures.

 

Biggest problem is the throttle linkage - still not happy with mine.

 

Click the project link in my sig for full pics.

[Sandy 189]

Colin Satchell makes a complete manifold/45mm bodies/trumpets/fuel rail/filter backplate/throttle linkage set up for all 16v XU's for £600, hardly worth messing about with bike bodies?

[B1ack_Mi16 67]

Colin Satchell makes a complete manifold/45mm bodies/trumpets/fuel rail/filter backplate/throttle linkage set up for all 16v XU's for £600, hardly worth messing about with bike bodies?

 

That's rather cheap, is that the setup used on that 2.2 that dynoed 240bhp?

 

Any pics of it?

[Sandy 189]

The 2.2 actually had Jenveys carried over from the previous 1.9, but the 234bhp 2.0 we did recently has them and numerous others. Twin injectors can be integrated quite easily. This set up allows more tract length than the Longmans/Jenvey manifold in the 205, without bonnet clearance problems.

 

Here they are on the 2.0:

 

http://noboost.com/temp/sandy/Beacham.JPG

Edited July 20, 2007 by sandy309

[welshpug 1,622]

The 2.2 actually had Jenveys carried over from the previous 1.9, but the 234bhp 2.0 we did recently has them and numerous others. Twin injectors can be integrated quite easily. This set up allows more tract length than the Longmans/Jenvey manifold in the 205, without bonnet clearance problems.

 

Here they are on the 2.0:

 

http://noboost.com/temp/sandy/Beacham.JPG

 

they look nice and low there, have you got any record of how the longer tracts affect the torque/power relationship?

[eeyore 0]

we designed the manifold to sweep downward so we could fit the long length and still get it under the bonnet, im currently working on a fabricated manifold that will fit in under the slam pannel with a filter on. Hopefully this will simplify mi/gti6 conversions. im very keen on useing the long length as everything weve used it on has performed well

[CaM 0]

thought about using toyota 4age 20v bodies? that's what I'm gonna be doing in a month or so

[Guest marky mark]

a question that kinda goes along these lines but dont know if its worth it

 

only being 18 going on 19 ive got a 1.9 gti and was wondering would bike bodies be decent gains on the 1.9 as i know a company who will do them for me for reasonable prices but just thinking wether its worth it or not

[Richie-Van-GTi 70 2 Cars]

yes you will see decent gains from a good setup, hard to give any exact figures as theres too many variables but I would say with mappable ignition and fuel using well sized bodies you could see an extra 20bhp on a 1.9 quite easily. I wouldnt be too concerned with actual figures though, its the driveability that is the biggest point, you can dispose of all the gremlins that dizzy and AFM's give regarding things like pinking, kangarooing, lumpy idles, hesitations etc, not to mention the induction noise

[VisaGTi16v 1]

Sandy: What else do you need with that £600 setup, presumably a full ecu thats a couple of hundred or more or can you run them as a basic carb like set up using the 8v dizzy and coil etc? and just to confirm, it will fit 1.9 and 2 litre Mi16's as well as a GTi6 head?

Edited July 23, 2007 by VisaGTi16v

[Dream Weaver 2]

Colin Satchell makes a complete manifold/45mm bodies/trumpets/fuel rail/filter backplate/throttle linkage set up for all 16v XU's for £600, hardly worth messing about with bike bodies?

 

Sounds interesting Sandy, any more details, pics, price list etc?

 

Is that all brand new stuff or is it old carbs that have been converted or something? Does it come with a filter as well as a backplate as that was the most expensive bit if mine at over £100?

 

Where can the kit be ordered?

[Sandy 189]

Any TB set up is going to need programmable management including mapped ignition, it's the main improvement with full management. Retaining the distributor (I presume you mean the Mi16 fixed type) is pointless, a twin coil pack is more reliable and cheap. Retaining a conventional distributor would be absolute madness. So additionally you do need an ECU, ECU loom and sundries like fuel hoses, throttle cable etc.

 

Colin's going to sort some pics out. It's all new and an absolute bargain frankly. The quality of his fabrication is top drawer. The filter element isn't included. If you're serious, PM Colin, he's "eeyore" on here.

[Dream Weaver 2]

Cool, I reckon he could sell plenty of kits at that money.

[Sandy 189]

Alot of them out there already, public service manufacturing!

[VisaGTi16v 1]

Sorry for the stupid questions So you are looking at at least what, £400 on top for something like a megasquirt with the extra bits you mention to maybe double that with a emerald? I guess/hope there are standard maps which work "ok" out there that you can use so dont have to do loads of expensive rolling road time unless you want those last few ponies if your engine isnt that heavily modified internally

[kyepan 291]

has anyone found out if the pulsar throttle bodies fit?

[Dream Weaver 2]

Sorry for the stupid questions So you are looking at at least what, £400 on top for something like a megasquirt with the extra bits you mention to maybe double that with a emerald? I guess/hope there are standard maps which work "ok" out there that you can use so dont have to do loads of expensive rolling road time unless you want those last few ponies if your engine isnt that heavily modified internally

 

My Emerald cost about £900 including the bits for the wiring loom, which I then had to build. It was another £250 for basic mapping which turned out ot be a waste of money (NOT done at Emerald I hasten to add).

 

The whole bodies and ECU thing was a waste of money for me as I'll never use them to their potential, but it was all done when I had too much dispoable income and a very small mortgage/no young lad to look after

 

Apart from the noise they make and the better throttle response/more power up the rev range, I don't think TB's give enough of an advantage over a std setup to warrant the cost unless your competing with them. My car isn't any quicker than a GTI-6 or Mi with cams/std induction in the real world.

[Sandy 189]

Visa- the bodies themselves aren't really the expensive bit! I'm sure there are many happy Megasquirt users, but if you aren't into it yourself, save the extra for an ECU that's popular with Mappers.

 

Dreamweaver- I think the process you've been through perhaps leaves a sour taste. I've run several road cars now with well thought out TB's on standard engines and have massively enjoyed all of them. TB's are to me, more than just a power upgrade; standard or tuned single throttle engines are never as engaging IMO, neither in terms of delivery or noise. The critical thing is getting it right though; I've seen some poorly executed and sometimes comicly over complicated set ups, that simply aren't as effective as they could be and often not reliable. Another aspect of this is mapping. Getting good mapping isn't easy, even recommendation can't ensure a good result, but this is just as true of tuned single throttle engines of course. Consider how much people often throw at head/cams/springs/manifolds/re-maps etc, to get as less impressive spread of power than TB's can produce on the standard engine with more respectable economy and resale value on the components.

[eeyore 0]

All of the people i know that were unhappy with there throttle body conversions had not had them set up properly, lots of people havent got up to speed with mapping yet but are still takeing it on. leaveing customers unsattisfied.

[Richie-Van-GTi 70 2 Cars]

whilst the 2 gurus are on this thread can I get one of you to expand a bit on the basics of mapping TB'? Is there ideal AFR to aim for as Ive heard variations around the 12.5 to 13.5 marks but also heard tales of the correct AFR changing according to RPM etc. Also is max ignition advance best throughout for an all out drive or should it still retain some form of curve in advance for best performance?

[VisaGTi16v 1]

I would love to get TB's one day but I think its quite a way off

[Sandy 189]

Visa- No point in doing it until you can do it properly, I think all the people on here who have set out to do it on the cheap have probably ended up either scrapping the idea or spending as much as anybody else. I'm sure it can be done, but even with all the resources I have at my disposal, I don't save much on the "full cost".

 

Richie- Dave Walkers book is a good start, it certainly was for me back in the day. Mapping is learning though, every time, every single engine is different and it depends if you want merely acceptable or refined results, I'm still refining the Trio's set up after 12,000 miles; but obviously the margin of improvement gets smaller and smaller!

But to give you an idea (for an NA engine, as I do it), as a general rule 14.7:1 up to about 50% throttle, 13.5:1 up to 80%, 12.8:1 to full. You can run leaner at part throttle, but it will take alot of refinement to make it smooth, running slightly richer at full throttle can increase power slightly by the extra cooling effect, but it's wasteful and the extra fuel often ends up in the oil. My Honda engine seems happiest around 13.2:1 at full throttle, probably slightly less power than 12.5:1, but it feels much cleaner. This is often true of modern heads and highish CR, you might also find that 15.8:1 at cruise is fine, but you need alot of transient enrichment to avoid it leaning out badly when you press the throttle. Conversley, medium CR engines with cams uprated might need significant enrichment to reduce misfires at light throttle. This is because the charge is low density and the flame travel is sporadic and slow. Extra fuel can help reduce pocketing of the air, which in turn helps flame travel and reduces the problem. The flip side is, you'll struggle to run low enough transient enrichement to eliminate black smoke during quick throttle openings. I had one car that had to be set up like this and is was frustrating! It was even more frustrating when it was video'd on track and casual observers criticised it. The only real solution is to raise CR.

Ignition wise, this is an absolute minefield! Every single engine has different ignition advance requirements, it's difficult to even generalise really. This is why I become slightly agitated by map sharing, it's a risky business. The same goes for "self mapping" ECU's, the AFR is an easy way to calculate the fuel map, but the ignition map is really what it's all about and even with a knock sensor operational, the map needs to be pretty accurate to start with. A good example recently was two 205's with 45DHLA and 45DCOE carbs that I fitted and mapped ignition ECU's on. The first was a GTi6 engine with small chokes. The full throttle curve I settled on was essentially a steady climb from 2000-7000 with a gentle bulge to it. The next was an Mi16 with large chokes and I started work with the GTi6 map; it was hopeless, some of the lower sites around 2000rpm needed as much as 20 degrees added to run clean. Then as the chokes started to work around 4000 rpm, the advance had to drop down to match the improved charge, then climbing again gently towards 7000rpm. If you used this latter map in the GTi6, it would melt something, no question.

However, if you want to just get it running, for a 16v try the following:

1000 6

2000 12

3000 20

4000 25

5000 27

6000 28

7000 28

Avoiding full throttle until you can get it properly mapped.

Edited July 24, 2007 by sandy309

[Richie-Van-GTi 70 2 Cars]

Awesome reply Sandy, hopefully that should give me and other members running MS somewhere to start. Im hoping to use megatune with the wideband so I can road map the car to a high enough standard in order to minimise and RR time.