Elite 2500 PnP on FD RX7
Hey everyone. Helping out a buddy who just installed his PnP Elite 2500 after swapping out an Adaptronic unit. He's running a half bridge motor with stock twins and your typical bolt ons.
Few issues we noted from the latest basemap that is posted: -Clutch switch does not register: Do we need to change anything to get this to show when he's pressing the clutch? -Vehicle speed does not register: Same as above -Wideband input: Can we use the 5v output from his AEM UEGO to the narrowband input and change the selection or is it advised to wire it elsewhere? Any advise you guys could give would be greatly appreciated. Other than that, the car seems to respond very well to minor adjustments and I'm pretty excited to see how it performs with a professional behind the keyboard! |
Figured out the wideband. Wired up to AVI4. Still open on the VSS and clutch switch.
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Bridgeport on stock twins? Why?
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Originally Posted by TwinCharged RX7
(Post 12305899)
Bridgeport on stock twins? Why?
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Originally Posted by TonyStarkz
(Post 12305201)
Hey everyone. Helping out a buddy who just installed his PnP Elite 2500 after swapping out an Adaptronic unit. He's running a half bridge motor with stock twins and your typical bolt ons.
Few issues we noted from the latest basemap that is posted: -Clutch switch does not register: Do we need to change anything to get this to show when he's pressing the clutch? -Vehicle speed does not register: Same as above -Wideband input: Can we use the 5v output from his AEM UEGO to the narrowband input and change the selection or is it advised to wire it elsewhere? Any advise you guys could give would be greatly appreciated. Other than that, the car seems to respond very well to minor adjustments and I'm pretty excited to see how it performs with a professional behind the keyboard! I know you don't want to hear this...but my best advice is to NOT run the half bridge when attached to the stock twins. The factory twin manifold is a pressure and heat trap that will result in extremely high preturbine backpressure and high EGTs due to it not being capable of handing the increased flow of the half bridge. Assuming the bridge has intake/exhaust port overlap (as most do), if preturbine backpressure exceeds intake manifold pressure you risk ingesting the exhaust gas into the intake stroke as it will be forced in by the higher pressure in the exhaust. This will drive up internal temperatures and can cause you to prematurely cook your motor and warp your seals resulting in loss of compression should it last that long. The extremely hot re-ingested exhaust gas will significantly bring UP the overall temperature of the combustion mixture which makes you WAY more likely to experience detonation, or if it is hot enough it can auto-ignite the mixture prematurely from just contact with the gas...either situation can result in some real nasty apex seal failure. Its a REALLY bad setup for the longevity of the rotary engine and it may cause so much damage to the engine that by the time you're ready to go single you need a single and a new motor. At the very least you should get a backpressure sensor and some egt bungs and tune for as low EGT as possible and stop at any point you see backpressure go much above 1.5:1. Skeese |
Originally Posted by Skeese
(Post 12306464)
I know you don't want to hear this...but my best advice is to NOT run the half bridge when attached to the stock twins. The factory twin manifold is a pressure and heat trap that will result in extremely high preturbine backpressure and high EGTs due to it not being capable of handing the increased flow of the half bridge. Assuming the bridge has intake/exhaust port overlap (as most due), if preturbine backpressure exceeds intake manifold pressure you risk ingesting the exhaust gas into the intake stroke as it will be forced in by the higher pressure in the exhaust. This will drive up internal temperatures and can cause you to prematurely cook your motor and warp your seals resulting in loss of compression should it last that long. The extremely hot re-ingested exhaust gas will significantly bring UP the overall temperature of the combustion mixture which makes you WAY more likely to experience detonation, or if it is hot enough it can auto-ignite the mixture prematurely from just contact with the gas if it is hot enough...either situation can result in some real nasty apex seal failure.
Its a REALLY bad setup for the longevity of the rotary engine and it may cause so much damage to the engine that by the time you're ready to go single you need a single and a new motor. At the very least you should get a backpressure sensor and some egt bungs and tune for as low EGT as possible and stop at any point you see backpressure go much above 1.5:1. Skeese Funny enough we've been battling a mysterious cooling issue and I wonder if your points are a contributing factor. For the life of us, we can't understand why this car runs so hot. We've bled, re-bled , flushed and done just about all the cooling checks we could. Either way, he's already started the process of moving away from his current turbo setup. Thanks again Skeese! |
Originally Posted by TonyStarkz
(Post 12306532)
Funny enough we've been battling a mysterious cooling issue and I wonder if your points are a contributing factor. For the life of us, we can't understand why this car runs so hot. We've bled, re-bled , flushed and done just about all the cooling checks we could.
Either way, he's already started the process of moving away from his current turbo setup. Thanks again Skeese! As far as the cooling issue, I'm not sure that its entirely related given that you mentioned you're still working base map setup and such and I'm assuming not pushing the car. It sounds to me like it may be in the cooling setup itself or that you need to possibly tweak the tune to drive the fans differently. If you can describe the cooling issue with when its happening and what temps are involved we can troubleshoot it. I'd be glad to take a look at the tune file and look it over to try and answer your other questions and give any other pointers I think would be helpful. PM me for my email if you want to. Skeese |
It has nothing to do with running factory twins on a bridgeport. Done heaps of them. They actually make great power and have an excellent powerband.
Your cooling issue is elsewhere. |
Originally Posted by Skeese
(Post 12306575)
No problem man. Don't hesitate to ask if you have any questions on turbo setup and sizing. Getting the right turbo setup is really a balancing act between your goals, your motor stats, what you do and dont want from your car, what best suits the rotary platform at the level you're going to be asking it to perform at, and your budget.
As far as the cooling issue, I'm not sure that its entirely related given that you mentioned you're still working base map setup and such and I'm assuming not pushing the car. It sounds to me like it may be in the cooling setup itself or that you need to possibly tweak the tune to drive the fans differently. If you can describe the cooling issue with when its happening and what temps are involved we can troubleshoot it. I'd be glad to take a look at the tune file and look it over to try and answer your other questions and give any other pointers I think would be helpful. PM me for my email if you want to. Skeese
Originally Posted by rx72c
(Post 12306715)
It has nothing to do with running factory twins on a bridgeport. Done heaps of them. They actually make great power and have an excellent powerband.
Your cooling issue is elsewhere. |
Originally Posted by rx72c
(Post 12306715)
It has nothing to do with running factory twins on a bridgeport. Done heaps of them. They actually make great power and have an excellent powerband.
Your cooling issue is elsewhere. Skeese |
Originally Posted by rx72c
(Post 12306715)
It has nothing to do with running factory twins on a bridgeport. Done heaps of them. They actually make great power and have an excellent powerband.
Your cooling issue is elsewhere. |
Stock sequential twins on a bridge port would be a bad idea because with the exhaust switching valve closed the rear exhaust port does have a constricted and tortuous path into the little 0.60AR primary turbo. Not ideal for a motor with overlap.
Parallel stock twins on a bridge port is a decent budget set-up for both power (400rwhp) and reliability. Each exhaust port has its own 0.60AR turbo for a combined 1.20AR- its more free breathing than whatever 400rwhp single turbo you are going to bolt on. |
Originally Posted by BLUE TII
(Post 12307113)
Stock sequential twins on a bridge port would be a bad idea because with the exhaust switching valve closed the rear exhaust port does have a constricted and tortuous path into the little 0.60AR primary turbo. Not ideal for a motor with overlap.
Parallel stock twins on a bridge port is a decent budget set-up for both power (400rwhp) and reliability. Each exhaust port has its own 0.60AR turbo for a combined 1.20AR- its more free breathing than whatever 400rwhp single turbo you are going to bolt on. I feel like there's no reason to put up with the downsides of a bridge to be settling for 400hp. Skeese |
Problem is you'll run out of compressor(s) with them at 400ish max with them, and you can go alot deeper with a modern mid size single and still outspool the twins on the low end as well. I feel like there's no reason to put up with the downsides of a bridge to be settling for 400hp. Skeese Only reasons I can see is if you think the downsides of the bridge port are the upsides (sound, flames etc) or you are using tuning/running a bridge on parallel twins as a step toward a planned single set-up. |
I didn't recommend doing it.
Simply said that I have done heaps of them as people do there engines first and then the rest of the car in stages as most can't afford to drop 50k in one go. They work and make around 30hp more then the street ports on the same boost and tend drop off alot later in the rev range compared to a street port. IT DOES NOT CAUSE COOLING SYSTEM ISSUES....lol where there wasn't one in the first place. |
Originally Posted by rx72c
(Post 12309489)
I didn't recommend doing it.
Simply said that I have done heaps of them as people do there engines first and then the rest of the car in stages as most can't afford to drop 50k in one go. They work and make around 30hp more then the street ports on the same boost and tend drop off alot later in the rev range compared to a street port. IT DOES NOT CAUSE COOLING SYSTEM ISSUES....lol where there wasn't one in the first place. Skeese |
The stock exhaust manual in parallel mode is not a bottleneck- it is a straight shot from the exhaust port to the turbo exhaust housing with a decent shaped change from round to rectangle port.
The twin turbo exhaust housings themselves are a bottleneck just as a turbo exhaust housing for a single is a bottleneck. Put the two twin turbo housings side by side and they don't look that different from a T4 divided turbo exhaust housing. But, I agree there is a bottleneck in the stock twins somewhere- otherwise people would be able to make more power with them than they have when they upgrade the compressor sides to flow more. My theory is that the combined turbine outlets and lack of adequate wastegate are probably the big bottlenecks on the stock twin turbo exhaust housings for making power. I would love some flowbench data on the stock twin turbo ehxuast housings with and without the center merge piece. We have seen that adding an external wastegate to parallel twins can pick up ~50rhwp through Ball joint's project. |
Pressure sensor in the dump pipe tells all. Restriction isn't in the exhaust manifold even when running sequential. :)
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Originally Posted by rx72c
(Post 12317218)
Pressure sensor in the dump pipe tells all. Restriction isn't in the exhaust manifold even when running sequential. :)
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rx72c Pressure sensor in the dump pipe tells all. Restriction isn't in the exhaust manifold even when running sequential. https://www.rx7club.com/images/smilies/smile.gif You put a pressure sensor in the stock exhaust manifold and in the downpipe and determined the exhaust restriction was between the exhaust wheel and the downpipe and not the exhaust wheel and the engine port? When running on the primary turbo alone? I am interested in your findings. I run in a racing class that requires stock engine and stock turbos, but allows any exhaust manifold and removing the turbos from the center merge section. |
Dump pipe and turbine wheels are the restrictive components from what I have seen
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TPS VS MAP ends up in a much better drive and idle without compromising either.
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Going to a TPS-Load based tune does have its advantages on a big port rotary, but only if you've got the skills to tune it currently. Initial tuning using tps as your load source can prove to be a good bit more difficult than a map based tune.
Personally, when making a tps load based tune I set up the main fuel table to be TPSxRPM and then have a seperate boost compensation table that adds additional VE to the fuel calculation starting when you cross into positive pressure. I have managed to tune my semi port 2 rotor that only pulls like 7" of vacuum to idle and drive perfectly fine using a map based tune and suspect the only real benefit of changing to a TPS tune being better throttle response. You can go either route and end up with a quality tune and well driving car. Skeese |
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