can anyone see why this wont work?
Discussion
In preparation for fitting a supercharger to my 4.5 Cerb I have modified a 4.2 inlet system. The butterflies, spindles, TP have all been removed and 2 cast aluminium plenums have been fitted. I have used 62mm Throttle bodies to each plenum.
I only want to run the engine N.A. at present. Do you think the AJP and the MBE can be mapped to make this N.A setup work or am i expectng to much?
Looks good Paul. Although I tend to think heat soak might be a problem with those pleunms directly over the exhaust manifolds. Fine under normal driving but might cause probs at idle or in traffic.
Can't think of any immediate mechanical problems, just make sure you've blocked off all the holes where the throttles used to be so you're not chasing air leaks.
Unless you've got all the software for remapping the MBE ECU live, which I doubt, I recon it'll be an up hill struggle to get it running right. Far better to opt for an Emerald ECU and be able to adjust everything easily and quickly.
I think your mapping problems will come on part throttle and transients. With the throttle position further forward you've got a lot more air volume behind the throttle plate compared to the original location. Your mapping will basically be trying to predict this air movement.
The original MBE is an Alpha N configuration, just engine speed and throttle position to predict the amount of air and then add the correct fueling. With the Emerald, you could use a MAP sensor to give a better overall indication of the air movement through the engine. Like a say, would make it much easier to map.
Rich.
Can't think of any immediate mechanical problems, just make sure you've blocked off all the holes where the throttles used to be so you're not chasing air leaks.
Unless you've got all the software for remapping the MBE ECU live, which I doubt, I recon it'll be an up hill struggle to get it running right. Far better to opt for an Emerald ECU and be able to adjust everything easily and quickly.
I think your mapping problems will come on part throttle and transients. With the throttle position further forward you've got a lot more air volume behind the throttle plate compared to the original location. Your mapping will basically be trying to predict this air movement.
The original MBE is an Alpha N configuration, just engine speed and throttle position to predict the amount of air and then add the correct fueling. With the Emerald, you could use a MAP sensor to give a better overall indication of the air movement through the engine. Like a say, would make it much easier to map.
Rich.
Seconded, the Alpha N system has no correlation between throttle angle and flow when used in a forced induction system. Totally unsuitable, use and Emerald or similar. Emerald is probably easier as they have one ready made and setup for the AJP odd firing angles.
Syncning the throttle plates may be problematic in your setup. I went for a single 100MM body.
EDIT,
re-read your post, yes it may work OK as a NASP setup provided you use original TPS's Will not be very accurate though as the flow rates may not be identical to the original for a given throttle angle. Suggest not giving it to much right foot as if it goes too lean it could destroy itself, the correctives may not be able to move far enough to fix the problem. I think on balance I would still go direct to an Emerald K3, expensive engine to screw up.
Syncning the throttle plates may be problematic in your setup. I went for a single 100MM body.
EDIT,
re-read your post, yes it may work OK as a NASP setup provided you use original TPS's Will not be very accurate though as the flow rates may not be identical to the original for a given throttle angle. Suggest not giving it to much right foot as if it goes too lean it could destroy itself, the correctives may not be able to move far enough to fix the problem. I think on balance I would still go direct to an Emerald K3, expensive engine to screw up.
Edited by fatjon on Friday 21st May 12:12
At last some feedback. Although this set up looks simple it has already defeated one mapper of the TVR mbe. It would appear a straight foward setup but must be introducing issues that the mbe / engine find difficult to handle.
The car starts and runs rough above 2000rpm. Despite adjusting the fuelling levels it constantly runs rich at lower speeds despite very small injector dwell times.
All sorts of theories have been put foward, fuel pressure, injectors, plenum design, cam overlap etc etc. Will try again and keep you all posted with the developments. The TVR/ mbe mapping specialsts all believe the mbe should be able to handle this set up. If changing to the emerald will solve all then I am happy to do this but will wait until the new K6 unit comes out in a few weeks.
The car starts and runs rough above 2000rpm. Despite adjusting the fuelling levels it constantly runs rich at lower speeds despite very small injector dwell times.
All sorts of theories have been put foward, fuel pressure, injectors, plenum design, cam overlap etc etc. Will try again and keep you all posted with the developments. The TVR/ mbe mapping specialsts all believe the mbe should be able to handle this set up. If changing to the emerald will solve all then I am happy to do this but will wait until the new K6 unit comes out in a few weeks.
why not email dave, aka dnb on here, I made him a pair of airboxes with twin 64mm throttle bodies on his 5oo griff, okay so it was a rv8, but he still had a few issues getting it set up properly, which he solved himself, and now goes like the clappers and much more responsive than before, so he may have a few ideas which could be of help to you.
I will email dnb to see if he has any ideas. Thanks.
Fatjon.... how's the twin turbo comming on. I presume you are using an emerald from your reply, are you still using the original throttle butterfly setup. The latest info I have is its only the low rpm (less than 2000rpm) that is proving a nightmare to sort out. The theory is that the cylinders are robbing each other of air at low speeds?. Spent a lot of time on this project, it will be a real shame if the issues cant be resolved.
Fatjon.... how's the twin turbo comming on. I presume you are using an emerald from your reply, are you still using the original throttle butterfly setup. The latest info I have is its only the low rpm (less than 2000rpm) that is proving a nightmare to sort out. The theory is that the cylinders are robbing each other of air at low speeds?. Spent a lot of time on this project, it will be a real shame if the issues cant be resolved.
Looking good!!
If it is robbing air from the other cylinders, then could you squeeze in some reed valves??
Something like these perhaps?
http://cgi.ebay.co.uk/Mercury-Mariner-Reed-Valve-A...
Might be able to find a size that could be fitted inside the plenum???
If it is robbing air from the other cylinders, then could you squeeze in some reed valves??
Something like these perhaps?
http://cgi.ebay.co.uk/Mercury-Mariner-Reed-Valve-A...
Might be able to find a size that could be fitted inside the plenum???
Hello
I'd have said that you could to go sequential injection to fix it, you can quite easily rig up a sensor to look at 1 tall bolt on the cam sprocket to give the correct phase. this will typically allow a leaner fuel mix as well and on highly tuned engines will liberate power.
If you don't fancy this try adding a small vertical 'fence of about 10mm high between cyls 1 & 2 and 3 & 4 as this should help separate the cylinder interaction
I'd have said that you could to go sequential injection to fix it, you can quite easily rig up a sensor to look at 1 tall bolt on the cam sprocket to give the correct phase. this will typically allow a leaner fuel mix as well and on highly tuned engines will liberate power.
If you don't fancy this try adding a small vertical 'fence of about 10mm high between cyls 1 & 2 and 3 & 4 as this should help separate the cylinder interaction
The Plenums been welded up so i'm snookered on any internal mods at the moment.
I'll give it one more go at a specialist TVR mapper and see what he makes of it.
If its a no go I will shelve the project till next year otherwise i wont get to use the car.
I will update the post when I get some more info.
I'll give it one more go at a specialist TVR mapper and see what he makes of it.
If its a no go I will shelve the project till next year otherwise i wont get to use the car.
I will update the post when I get some more info.
As I said I took the car to a mapping specialist who could'nt get it to run either.
All sorts of theories were put foward but they gave up on the project.
Joo then said he would be interested in having a go.....delivered the car on a trailer, left it with him 2 weeks later I drove my cerb home.
I dont think I have ever met a nicer guy than Joo's He is a absolute gem. He mapped it using the MBE system. Had to put a 2 inch balance pipe between each plenum. Produces 380bhp in this format which is exactly the same as the original 4.5 inlets and boxes.
It drives almost the same as a standard car, the only slight difference is at initial throttle opening, the new system seem a bit too eager and the car very quickly pulls away.
Hopefully will get all these nigggles sorted when it is mapped with the supercharger connected.
All sorts of theories were put foward but they gave up on the project.
Joo then said he would be interested in having a go.....delivered the car on a trailer, left it with him 2 weeks later I drove my cerb home.
I dont think I have ever met a nicer guy than Joo's He is a absolute gem. He mapped it using the MBE system. Had to put a 2 inch balance pipe between each plenum. Produces 380bhp in this format which is exactly the same as the original 4.5 inlets and boxes.
It drives almost the same as a standard car, the only slight difference is at initial throttle opening, the new system seem a bit too eager and the car very quickly pulls away.
Hopefully will get all these nigggles sorted when it is mapped with the supercharger connected.
Gassing Station | Cerbera | Top of Page | What's New | My Stuff