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S5 N/A power...
Well if you read my other post I have ditched the weber setup from my 88 Rx7 with s5 motor. Im now using my s5 block with everything from an s4 like LIM, UIM and all the electronics. Im now wondering, with out opening up the motor what can I do to get this car to high 14s? I want to run around 14.6-14.9, Ive seen on dragtimes an 88 gxl na run 14.8 with just racing beat headers and an exhaust. Is that possible? My current mods are OBX headers, borla catback, stock intake with cone filter. I also have a GTUs 4.3 LSD diff, and my car has a total weight of around 2400. What kind of times can I see from this alone? And what times can I see from adding a 50 shot?
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Converting to S5 intake manifolds will be good for about ~15 bhp: http://homepage.mac.com/carldavis/intake.html.
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Being that the S4 came with 146 BHP and the S5 came with 160 BHP (N/A) engines I would have to say that you are just a little high on the expected gain. Their is a difference in the S5 ECU and MAF that allows the 160 BHP coupled with the VDI intake design. :)
The S4's have the AFM which is some what restrictive versus the free flowing MAF design. 10 BHP may be more of a conservative number. :)
Originally Posted by RotaryRocket88
(Post 10153738)
Converting to S5 intake manifolds will be good for about ~15 bhp: http://homepage.mac.com/carldavis/intake.html.
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Ditch the "Cone" filter. It has been proven that putting a "Cone" filter does nothing and perhaps loses HP. The stock air box and a KN filter would be your best bet. The stock air box is designed to be a cold air intake by shielding the air coming in from the heat that is in the engine compartment.
Even the expensive KN FIPK system for these cars do not offer any HP gain before and after information if that tells you anything. :-) |
I have the s5 motor
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according to that calculator at 140whp weighing in at 2400 will put me at 14.8
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Originally Posted by Rx-7Doctor
(Post 10153761)
Being that the S4 came with 146 BHP and the S5 came with 160 BHP (N/A) engines I would have to say that you are just a little high on the expected gain. Their is a difference in the S5 ECU and MAF that allows the 160 BHP coupled with the VDI intake design. :)
The S4's have the AFM which is some what restrictive versus the free flowing MAF design. 10 BHP may be more of a conservative number. :) |
It's a combination of things but mainly due to the "VDI" system which makes more HP @ 500 RPM higher than the S4 models.
Originally Posted by 1sick13b
(Post 10153815)
I thought the bump in horsepower came from the higher compression rotors
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so how much u think my car will be rated with the s4 system and s5 block
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probably the same or less. you're using the wrong ECU for that engine that has higher compression and should have a higher redline.
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Without a "Dyno" I have no idea.
Have no idea how much that OBX header adds and your exhaust. Maybe you have around 165 BHP with the header and exhaust? |
I'd be guessing you're pretty close to S4 power levels - most of the gains in S5 motors come from the higher redline combined with the better-flowing VDI intake manifold, and appropriate ECU controlling it all.
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Your way off base here!
Their is only a .3 difference in compression and that does not affect much of anything. The VDI system is what makes more HP at the higher RPM level. quote=Cordt;10154001]probably the same or less. you're using the wrong ECU for that engine that has higher compression and should have a higher redline.[/quote] |
that doesn't mean anything....what I said is still valid. why would i bring up the VDI system when others have already mentioned it?
like mentioned before, there are many things that add up to it. higher redline being a good contributor, which would be negated by not having the right ECU. |
Read about how the VDI works and you will understand that the ECU does not factor in here!
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I know how it works....for the second time I'm not saying that is not a factor. Still, without the correct ECU you're losing 1000RPM of usable power.
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^ Ok if you say so! LOL
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first off why would you want to run 14's for.
are they dual cats/muffler or a single set up i wouldnt reccommend nitrous can you drop in a turbo and run 15-14 sure look tuning an n/a is costly but if you want to do it - do it all rotaries start in the exhaust it wont add alot but when coupled together with the correct amount of porting you can get gains from 15 to 30 hp, depending on the exhaust set up and how much porting was done. you could free up some hp to the tires by removing all acc. except the alt (obviously) lose weight ( carpets radio dash seats ect. ) whether or not your using an s4 or s5 engine it wont make a big diffrence once you start tuning. light weight fly wheel clutch drive shaft will free up some more hp to the tires(no it wont add horses just free up the ones you have pushing that heavy flywheel from there to the tires) there is alot you can do to run 14-15's is not al that hard although i dont fully understand the reason you might want to run 14's here are my 2 cents |
Im not trying to run really fast this car is mainly drift and auto cross, its just once in a while a group of friends go to the track and i dont want to be running high 15s to low 16s shit id be happy with a 15.0. I think i might just do the setup i had on my old gxl and do 6 port turbo or do a small shot of nitrous..
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Originally Posted by Rx-7Doctor
(Post 10153761)
Being that the S4 came with 146 BHP and the S5 came with 160 BHP (N/A) engines I would have to say that you are just a little high on the expected gain. Their is a difference in the S5 ECU and MAF that allows the 160 BHP coupled with the VDI intake design. :)
The S4's have the AFM which is some what restrictive versus the free flowing MAF design. 10 BHP may be more of a conservative number. :) As for the approximate horsepower number I gave, arguing 5 bhp is pointless. The numbers you've sited are for completely stock cars. With aftermarket exhaust/intake setups, those numbers will differ. You can refer to this thread from the archives if you'd like to see a dyno: https://www.rx7club.com/2nd-gen-archive-72/89-intake-swap-before-after-dyno-results-95492/. There is a gain of at least 10 WHP. This will certainly differ between cars, which is why an estimate of up to 15 BHP is not unreasonable in my book.
Originally Posted by Cordt
(Post 10154047)
that doesn't mean anything....what I said is still valid. why would i bring up the VDI system when others have already mentioned it?
like mentioned before, there are many things that add up to it. higher redline being a good contributor, which would be negated by not having the right ECU. |
As stated again- The AFM is "Somewhat" restrictive. This is not in reference to "Size" but how the Air enters and flows through. It has a "Flap" door as opposed to being a "Open" hole as with the MAF which does make a difference as to how air flows!
I am not arguing anything, I am pointing out realistic numbers. Of course HP numbers go up when exhaust is changed. The test with the Header added, the T/Body mod, the electric air pump added and the A/C removed cannot be validated as to the S5 intake adding anymore HP to the equation than without those mods. The HP numbers would have to be done in 3 tests to confirm this claim. Which means the above mods without the S5 intake would have to be Dyno'd then the S5 system installed to know the "True" HP increase because of the S5 system. :)
Originally Posted by RotaryRocket88
(Post 10155168)
If the AFM shape has any role, it is negligible. The S5 version actually has a smaller opening than the S4, but neither are an actual restriction. Neither AFM will not max out until about the 350whp mark, which has been demonstrated with Rtek 2.x turbo cars.
As for the approximate horsepower number I gave, arguing 5 bhp is pointless. The numbers you've sited are for completely stock cars. With aftermarket exhaust/intake setups, those numbers will differ. You can refer to this thread from the archives if you'd like to see a dyno: https://www.rx7club.com/showthread.php?t=95492. There is a gain of at least 10 WHP. This will certainly differ between cars, which is why an estimate of up to 15 BHP is not unreasonable in my book. The ECU doesn't determine redline; it determines where the RPM-limiter kicks in, which is higher than redline anyway. A stock S5 NA makes peak horsepower at 7000 RPM, which is still within the safe revving range for an S4 engine. The S4 intake manifold makes peak power at about 6500 RPM, which means by the 7000 RPM redline, there is a pronounced dip in power. Using the S5 manifold, the car pulls strong all the way to redline. I converted my S4 engine to use S5 manifolds, so you can trust me on this one. It was significant enough to feel. You just can't be afraid to redline the engine. |
Also as you can see their is a power loss indicated on the stock engine as it is rated at 146 BHP from the factory. Even with a high flow cat and non-restrictive muffler system. Probably due to the 5th 6th port system being blocked off on the stock set up!
Again though to verify this 2 dyno's would have to be done. One with the 5th 6th port system in place and working and then with it blocked off to determine what the actual starting HP was on the stock Engine. Then with all the mods after it is approx 1.71 more BHP only than a Stock S5 Engine? Something just does not add up here? So it now makes you wonder how much difference the S5 ECU and S5 MAF and slightly higher compression have in it's role in the total equation of HP? |
The S5 AFM isn't straight through. It has a moving cone inside that functions the same as the door in the S4 AFM. It's still a mechanical restriction design, and since the flow rates will be comparable, the difference in pressure drop between the 2 is negligible. If you are using the term MAF to denote a hotwire type or similar meter, neither the S4 or S5 is a MAF, they are both mechanical AFMs.
The compression ratio doesn't factor in to the ECU at all. The ECU is there to match the fuel delivery to the incoming air. Compression ratio doesn't change how much air the engine pulls in. |
I did not say that the compression ratio factors into the ECU nor the amount of air flow. Read the statement again-
So it now makes you wonder how much difference the S5 ECU and S5 MAF and slightly higher compression have in it's role in the total equation of HP? Does it say anything about compression having anything to do with the ECU or air being pulled in? NO!!!!!!!!!!!!!! It's a combination of all components and figuring out how much HP the combined components may play in the total HP equation of the S5 Engine. 3 This is not my first Rodeo guys and I am not going to have a pissing contest!
Originally Posted by MadScience_7
(Post 10155997)
The S5 AFM isn't straight through. It has a moving cone inside that functions the same as the door in the S4 AFM. It's still a mechanical restriction design, and since the flow rates will be comparable, the difference in pressure drop between the 2 is negligible. If you are using the term MAF to denote a hotwire type or similar meter, neither the S4 or S5 is a MAF, they are both mechanical AFMs.
The compression ratio doesn't factor in to the ECU at all. The ECU is there to match the fuel delivery to the incoming air. Compression ratio doesn't change how much air the engine pulls in. |
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