XR7 Dave
Registered User
Ok so I have this P O S DD. I got the motor out of a JY XR7 so I don't know much about it other than it more or less runs. Anyway so I'll give you some background on it.
When it was totally stock it ran about 15.5 or so at the track and put down a measly 185rwhp. Nice. Well anyway, so I ported the 89 blower and slapped a 10% pulley on it. Was rewarded with 204rwhp. My other bone stock XR7 used to make 210rwhp bone stock so this was a little depressing but anyway. It was making 15psi like this (stock exhaust) so I just chalked it up to plugged cats and didn't worry too much.
Well so later on I came across some parts cheap and decided to try them out. I got an MPII case (but no plenum) so I installed that and ported a stock 94 plenum to match. I took the 10% pulley off because I knew that was a recipe for trouble on the stock IC. I added a 255lph fuel pump and some 50lb injectors I had laying around. I got a home made raised top cheap somewhere so I put that on, and a used PP 75mm TB. I fabbed up a 3" intake tube from some cast off exhaust piping, and slapped an 85mm C&L on the end of it. I figured that as long as I didn't overdrive the blower it would be ok.
I was wrong. The thing made like 21psi or so and whooped out an amazing 227rwhp. As Ryan Zimmerly is my witness, it was not pretty.
I knew I had to do something with the exhaust so I scavenged a used (but pretty cool) cat back from Cory Binks' cast offs (sweet Borla's btw), added a resonator of sorts and some 2.0" Magnaflow downtubes with cats. I figured that would flow enough air and it would eliminate bad cats as a possible problem. Then I also ran across a Snow kit for cheap so I figured that might compensate for the crappy IC a little. So away we went. This combo was actually pretty sweet. It made about 250rwhp and about 15-16psi. On the dyno things looked pretty good. At the track it was a different story. This is how the car was set up for the 2011 SC Shootout and low and behold I could not break out of the 14's to save my life. Bogus. 250rwhp should be good for a solid high 13 but I was running 14.2-14.3 even with slicks.
Well so I figured the exhaust was kind of crappy with those small down tubes and I know the IC sucked (stock) so this past week when Phil was off on spring break I put him to work. We yanked out the exhaust and replaced it with another take-off system I had laying around that is composed of Kooks shorties, 2.5" mandrel downtubes, cats, a Magnaflow resonator, and 3" mid section and some Flow's out back. Looks bad to the bone, sounds worse, and just generally ... well anyway.
To that we added a genuine FMIC, actually the infamous one from my original 400rwhp build so I knew it would be good, and took the car back to the dyno to reap our rewards. Or weep, as the case may be.
I think it made 255rwhp. Still makes 16psi boost, so the exhaust wasn't causing any problems before, and frankly the car feels like a pig. I can't stand it.
It did make about 10rwtq more around 3000rpm, and about 10rwhp at 4800-5000rpm, but it actually lost some power at about 3800. Seems the headers might have some resonate impact at various rpms vs. the stock unported manifolds.
So there it is. I seem to be an epic fail when it comes to adding power to my junk. If nothing else, hopefully this makes some of you who are struggling to make HP feel better. It happens to everyone.
So what now? Well, I'm going to add a 10% pulley because it just doesn't have any sack down low. I figure it won't add any HP but if it will at least spin the tires now I'll be happy(er).
After that I think I'm going to rip the heads off because I suspect a leaking headgasket and put something better on there. I have an old cam laying around that I got somewhere and a set of reject ported heads that need a home. But that's a lot of work and I don't have time right now, so maybe I'll be able to bribe Phil with some cookies or something so he'll "do work" for me.
Well, that's all folks. I'm going to go back to the track when it's not raining and see if it's really as slow as I think it is..... I'll keep you updated.
When it was totally stock it ran about 15.5 or so at the track and put down a measly 185rwhp. Nice. Well anyway, so I ported the 89 blower and slapped a 10% pulley on it. Was rewarded with 204rwhp. My other bone stock XR7 used to make 210rwhp bone stock so this was a little depressing but anyway. It was making 15psi like this (stock exhaust) so I just chalked it up to plugged cats and didn't worry too much.
Well so later on I came across some parts cheap and decided to try them out. I got an MPII case (but no plenum) so I installed that and ported a stock 94 plenum to match. I took the 10% pulley off because I knew that was a recipe for trouble on the stock IC. I added a 255lph fuel pump and some 50lb injectors I had laying around. I got a home made raised top cheap somewhere so I put that on, and a used PP 75mm TB. I fabbed up a 3" intake tube from some cast off exhaust piping, and slapped an 85mm C&L on the end of it. I figured that as long as I didn't overdrive the blower it would be ok.
I was wrong. The thing made like 21psi or so and whooped out an amazing 227rwhp. As Ryan Zimmerly is my witness, it was not pretty.
I knew I had to do something with the exhaust so I scavenged a used (but pretty cool) cat back from Cory Binks' cast offs (sweet Borla's btw), added a resonator of sorts and some 2.0" Magnaflow downtubes with cats. I figured that would flow enough air and it would eliminate bad cats as a possible problem. Then I also ran across a Snow kit for cheap so I figured that might compensate for the crappy IC a little. So away we went. This combo was actually pretty sweet. It made about 250rwhp and about 15-16psi. On the dyno things looked pretty good. At the track it was a different story. This is how the car was set up for the 2011 SC Shootout and low and behold I could not break out of the 14's to save my life. Bogus. 250rwhp should be good for a solid high 13 but I was running 14.2-14.3 even with slicks.
Well so I figured the exhaust was kind of crappy with those small down tubes and I know the IC sucked (stock) so this past week when Phil was off on spring break I put him to work. We yanked out the exhaust and replaced it with another take-off system I had laying around that is composed of Kooks shorties, 2.5" mandrel downtubes, cats, a Magnaflow resonator, and 3" mid section and some Flow's out back. Looks bad to the bone, sounds worse, and just generally ... well anyway.
To that we added a genuine FMIC, actually the infamous one from my original 400rwhp build so I knew it would be good, and took the car back to the dyno to reap our rewards. Or weep, as the case may be.
I think it made 255rwhp. Still makes 16psi boost, so the exhaust wasn't causing any problems before, and frankly the car feels like a pig. I can't stand it.
It did make about 10rwtq more around 3000rpm, and about 10rwhp at 4800-5000rpm, but it actually lost some power at about 3800. Seems the headers might have some resonate impact at various rpms vs. the stock unported manifolds.
So there it is. I seem to be an epic fail when it comes to adding power to my junk. If nothing else, hopefully this makes some of you who are struggling to make HP feel better. It happens to everyone.
So what now? Well, I'm going to add a 10% pulley because it just doesn't have any sack down low. I figure it won't add any HP but if it will at least spin the tires now I'll be happy(er).
After that I think I'm going to rip the heads off because I suspect a leaking headgasket and put something better on there. I have an old cam laying around that I got somewhere and a set of reject ported heads that need a home. But that's a lot of work and I don't have time right now, so maybe I'll be able to bribe Phil with some cookies or something so he'll "do work" for me.
Well, that's all folks. I'm going to go back to the track when it's not raining and see if it's really as slow as I think it is..... I'll keep you updated.
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