CAMSHAFT SELECTION AND A BIT MORE
Discussion
gerjo said:
Wow, that's very expensive! Think I'll just have to live with the bad in-town manners, because for the rest I love the H404!
Any other possibilities to make my engine run smoother low-down? I heard that an Omex system won't always help.
Not realy no! after market ecu's will help slightly because you can retard the ignition around the point that the shunting is happening at, but its not a fix for a fast road cam!, i was a bit on the high side with the throttle bodies if you shop around you could get them for around the £5000 mark fitted and set up but this will probably be with emerald or something similar.
Hi gerjo
If you put better flowing heads on your engine now but kept everything else the same cam,induction etc.. it will drive the same in the way of manners, but it would make a lot more power, so what you can do is put a tamer cam in it so it drives like a pussy cat but it will go on to make the same bhp as you have now with an increase in low down torque, unfortunetly there arent any off the shelf heads you can buy for a road car to acheive this, i have a pair here i have been messing with for years welding them all up and changing the port angles and have cost me around £4000 so you can see how expensive it could get! you would be looking at around £2500 to replicate them...
Throttle bodies will significantly alter the way your car drives, if you ever get the chance to drive a car on either individual carbs or injection you would be amazed in the difference. but again by the time you have bought all the kit and installed them dont expect anychange out of around £7000 for an omex set up.
Any other possibilities to make my engine run smoother low-down? I heard that an Omex system won't always help.
Not realy no! after market ecu's will help slightly because you can retard the ignition around the point that the shunting is happening at, but its not a fix for a fast road cam!, i was a bit on the high side with the throttle bodies if you shop around you could get them for around the £5000 mark fitted and set up but this will probably be with emerald or something similar.
v8 racing said:
gerjo said:
Hi Rob,
Great stuff. So if I understand correctly, to make a RV8 (5.2 in my case) run smoothly (in town) but yet very powerful (e.g. with a H404) it will need a different head/valves or seperate throttle bodies.
Great stuff. So if I understand correctly, to make a RV8 (5.2 in my case) run smoothly (in town) but yet very powerful (e.g. with a H404) it will need a different head/valves or seperate throttle bodies.
Hi gerjo
If you put better flowing heads on your engine now but kept everything else the same cam,induction etc.. it will drive the same in the way of manners, but it would make a lot more power, so what you can do is put a tamer cam in it so it drives like a pussy cat but it will go on to make the same bhp as you have now with an increase in low down torque, unfortunetly there arent any off the shelf heads you can buy for a road car to acheive this, i have a pair here i have been messing with for years welding them all up and changing the port angles and have cost me around £4000 so you can see how expensive it could get! you would be looking at around £2500 to replicate them...
Throttle bodies will significantly alter the way your car drives, if you ever get the chance to drive a car on either individual carbs or injection you would be amazed in the difference. but again by the time you have bought all the kit and installed them dont expect anychange out of around £7000 for an omex set up.
Edited by v8 racing on Wednesday 28th March 10:03
spend said:
Can you run TB's with the Lucus ECU? I would have thought you would first have to install an alternate ECU, which might result in better manners anyway....
Dave
Dave
Unfortunetly no you cant rn the 14 cux on throttle angle, we tried but it just had so many flat spots it was a joke!
900T-R said:
Now this is really neat IMO, it looks like you could put a standard RV8 plenum on top and no one would ever notice bar the absence of a throttle body upstream from it...
I would have thought you could run throttle bodies and 14CUX as long as all the throttles drew through a common intake with an AFM? (You would almost certainly want a common intake anyway.) Sticking with the 14CUX would severely limit the people who can map it for you and also mean you don't get mapped ignition. You can add an extra ECU for the ignition, but if you're doing that I would have thought it was a no-brainer to use an ECU that can take care of the fuel too.
900T-R said:
Now this is really neat IMO, it looks like you could put a standard RV8 plenum on top and no one would ever notice bar the absence of a throttle body upstream from it...
Sweet
I always thought the the TB setup would be to high to get the plenum chamber on and still clear the bonnet, that pic appears to be a Griff engine bay.
GreenV8S said:
900T-R said:
Now this is really neat IMO, it looks like you could put a standard RV8 plenum on top and no one would ever notice bar the absence of a throttle body upstream from it...
I would have thought you could run throttle bodies and 14CUX as long as all the throttles drew through a common intake with an AFM? (You would almost certainly want a common intake anyway.) Sticking with the 14CUX would severely limit the people who can map it for you and also mean you don't get mapped ignition. You can add an extra ECU for the ignition, but if you're doing that I would have thought it was a no-brainer to use an ECU that can take care of the fuel too.
You can run 14 cux if you resort to boxing the trumpets back in via a plenum etc but whats the point of that? that trumpet base with the butterflies in certainly isnt new, nck first did in 1988 i believe, it was basically a cheap way to run open throttle bodies which it did ok ish, you still had the poor inlet manifold to contend with though, as for putting a plenum straight back on top i just dont get that?? apart from slightly helping on the overlap period you are going to hurt bhp more than just running a normal set up as not only do you have the restriction of the plenum each runner now has a spindle and butterfly in the way!.
v8 racing said:
though, as for putting a plenum straight back on top i just dont get that??
What's the alternative then, apart from having air filters poke straight through the bonnet, Tuscan racer-style? You've got to draw cold air from somewhere...
Oh, and I thought the point of having individual throttle butterflies for each cylinder as close as possible to the intake valves was instant throttle response rather than outright bhp
. Edited by 900T-R on Wednesday 28th March 18:13
I guess it would be an improvement with a larger volume air-box feeding from the meter/ induction pipe.
Going back to 8 throttle downdraft TBs, we are working on a new air-box system for RV8 with Jenvey throttle bodies, will have a single 100mm intake on the near-side so it would be possible to use a Meter if required.
P.S Good post Rob
Going back to 8 throttle downdraft TBs, we are working on a new air-box system for RV8 with Jenvey throttle bodies, will have a single 100mm intake on the near-side so it would be possible to use a Meter if required.
P.S Good post Rob
ACT said:
I guess it would be an improvement with a larger volume air-box feeding from the meter/ induction pipe.
Going back to 8 throttle downdraft TBs, we are working on a new air-box system for RV8 with Jenvey throttle bodies, will have a single 100mm intake on the near-side so it would be possible to use a Meter if required.
P.S Good post Rob
Going back to 8 throttle downdraft TBs, we are working on a new air-box system for RV8 with Jenvey throttle bodies, will have a single 100mm intake on the near-side so it would be possible to use a Meter if required.
P.S Good post Rob
How do Jenvey TB's compare with something like GSX1000 TB's which is what I was considering doing?
Edited by bluebottle on Wednesday 28th March 21:04
v8 racing said:
You can run 14 cux if you resort to boxing the trumpets back in via a plenum etc but whats the point of that?
Feeding the trumpets from a plenum doesn't seem like such a controversial idea, how else are you going to feed them with cold filtered air unless you stick them out through the bonnet? TVR do it and that seems to work OK? You'd need to pay attention to the restriction, but if you can engineer throttles into a trumpet base surely it's not asking much to stick a box over the top and pipe it out to the front.
Whether it would be sensible is another matter, I can't see any good reason to keep the CUX if you're making mods that are this dramatic. Surely you'd want to get rid of the AFM restriction, and get mapped ignition etc.
ACT said:
To my knowledge the Bike throttles are too small 38mm ?? , for monster engines you want 48mm
No bigger than that....
The bike ones are not big enough but again it all depends on what you want.
The costs are high because of the new manifold, 8 x the TB cost and the new ECU to help exploit them.
Also don't underestimate the skill needed to get them balanced and setup correctly.
I've been running TBs for 4 years now and there is no way I would go back to a plenum... unless it was attached to a supercharger which is exactly what I have right now.
Edited by shpub on Wednesday 28th March 22:25
GreenV8S said:
v8 racing said:
You can run 14 cux if you resort to boxing the trumpets back in via a plenum etc but whats the point of that?
Feeding the trumpets from a plenum doesn't seem like such a controversial idea, how else are you going to feed them with cold filtered air unless you stick them out through the bonnet? TVR do it and that seems to work OK? You'd need to pay attention to the restriction, but if you can engineer throttles into a trumpet base surely it's not asking much to stick a box over the top and pipe it out to the front.
Air temperature wasn't an issue with the 520SE with the throttle bodies surprisingly. And if you want them not to stick through the bonnet, John Eales has done a manifold that turns the TBs by 90 degrees and so reduce the height dramatically. I've seen the prototype and it looked extremely compact.
As for boxing in the TBs to make a plenum. That is exactly what is needed for forced induction. I now have a plenum fed by the supercharger which inturn feeds the 8 throttle bodies. No AFM. Mapped on manifold pressure/throttle position.
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