XR7 Dave
Registered User
I know that making an SC go fast (or quick as the case may be) can be a frustrating experience, especially for the beginner, so I thought I'd post some details about my latest escapade with "going slow".
My DD is a stock 89 5spd XR7. The previous owner put 3.27 gears and a 94 5spd trans in the car but other than that it has a JY motor in it with somewhere over 100K on it. It runs ok but has never dyno'd well. I'll dig up my sheets but I think it dyno'd around 185-190rwhp, bone stock. Since then I've put an MPII on it with MP plenum, 75mm TB, raised top, 3.5" intake, 80mm MAF, and 9" cone filter. I have 50lb injectors and a 255lph fuel pump to back it up. I did not overdrive the blower though because with the stock exhaust it was making a ridiculous amount of boost - like 20psi or something. I dyno'd it and the best I got was I think 225rwhp or something. I know, that was ridiculous and so I have since removed the MP plenum and replaced it with a stock plenum. It still makes something like 17psi but remember, stock exhaust and no OD on the blower.
In this form I have been daily driving the car using 87 octane fuel. Of course it was tuned accordingly, but I guess I wanted to prove that a stock exhaust doesn't blow headgaskets. These ones are original and they are doing fine so far. So anyway, I took it to the track just like this and while I did put 93 octane in the car I did not retune it. I was curious how it would run. Ya, how about bad. I ran 15.98 @ 88mph with a 2.45 60 ft. A better 60ft would probably have netted a 15.5 but that's pretty sad and I had no desire to try to find that 15.5, lol.
So I went ahead and retuned the car for the 93 octane. With adjustments to the tune and my driving technique (street tires) I managed to whittle it down to a 14.69 @ 94mph. This was still with a 2.24 60ft so I think 14.50's were in there if I could have gotten off the line better.
At this point I was semi happy because while it wasn't breaking any records, with ACT's approaching 180 during the runs, I just didn't think there was much if any more to be had. It was also a very warm day.
So then I decided that since the exhaust was dead quiet other than the swooshing sound, and the T-bird tips just look silly on an XR7, I needed to upgrade the exhaust. I bought the Magnaflow high flow downtubes because I know the car isn't going to make a ton of HP ever, and they are direct fit and I was short on time. To that we added a resonator and a used back half from Cory Bink's old setup. I figure it made 270rwhp for him so it should be good enough for me. To that we also added an IC fan and alcohol injection to hopefully cool things down enough that we could add some more timing for more powa. Too bad it didn't add up to much. I don't know if this motor is just that tired, or something else, but on the dyno all that only worked out to 25rwhp. I ended up with just a hair over 250rwhp. But it had to be enough because that's all there was going to be in the budget for stage 1.
This is the config in the car for the Shootout. I had hoped for 13.90's but it just didn't want to happen. I replaced the street tires for slicks and launching at 3500rpm the best I managed was 14.31 @ 95mph and a 2.0 60ft. Clearly there is more than one thing going wrong here, but I have to say that I think the car is quite off the mark.
On the dyno the car didn't want to take timing and on the track while the car felt ok it just didn't go like it should have. So there you have it, if you feel like your car isn't performing like it should, welcome to the club. I'll figure it out, but for now it's just slow.
My DD is a stock 89 5spd XR7. The previous owner put 3.27 gears and a 94 5spd trans in the car but other than that it has a JY motor in it with somewhere over 100K on it. It runs ok but has never dyno'd well. I'll dig up my sheets but I think it dyno'd around 185-190rwhp, bone stock. Since then I've put an MPII on it with MP plenum, 75mm TB, raised top, 3.5" intake, 80mm MAF, and 9" cone filter. I have 50lb injectors and a 255lph fuel pump to back it up. I did not overdrive the blower though because with the stock exhaust it was making a ridiculous amount of boost - like 20psi or something. I dyno'd it and the best I got was I think 225rwhp or something. I know, that was ridiculous and so I have since removed the MP plenum and replaced it with a stock plenum. It still makes something like 17psi but remember, stock exhaust and no OD on the blower.
In this form I have been daily driving the car using 87 octane fuel. Of course it was tuned accordingly, but I guess I wanted to prove that a stock exhaust doesn't blow headgaskets. These ones are original and they are doing fine so far. So anyway, I took it to the track just like this and while I did put 93 octane in the car I did not retune it. I was curious how it would run. Ya, how about bad. I ran 15.98 @ 88mph with a 2.45 60 ft. A better 60ft would probably have netted a 15.5 but that's pretty sad and I had no desire to try to find that 15.5, lol.
So I went ahead and retuned the car for the 93 octane. With adjustments to the tune and my driving technique (street tires) I managed to whittle it down to a 14.69 @ 94mph. This was still with a 2.24 60ft so I think 14.50's were in there if I could have gotten off the line better.
At this point I was semi happy because while it wasn't breaking any records, with ACT's approaching 180 during the runs, I just didn't think there was much if any more to be had. It was also a very warm day.
So then I decided that since the exhaust was dead quiet other than the swooshing sound, and the T-bird tips just look silly on an XR7, I needed to upgrade the exhaust. I bought the Magnaflow high flow downtubes because I know the car isn't going to make a ton of HP ever, and they are direct fit and I was short on time. To that we added a resonator and a used back half from Cory Bink's old setup. I figure it made 270rwhp for him so it should be good enough for me. To that we also added an IC fan and alcohol injection to hopefully cool things down enough that we could add some more timing for more powa. Too bad it didn't add up to much. I don't know if this motor is just that tired, or something else, but on the dyno all that only worked out to 25rwhp. I ended up with just a hair over 250rwhp. But it had to be enough because that's all there was going to be in the budget for stage 1.
This is the config in the car for the Shootout. I had hoped for 13.90's but it just didn't want to happen. I replaced the street tires for slicks and launching at 3500rpm the best I managed was 14.31 @ 95mph and a 2.0 60ft. Clearly there is more than one thing going wrong here, but I have to say that I think the car is quite off the mark.
On the dyno the car didn't want to take timing and on the track while the car felt ok it just didn't go like it should have. So there you have it, if you feel like your car isn't performing like it should, welcome to the club. I'll figure it out, but for now it's just slow.