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Does 18% HP gain in a manifold sound logical? +37 HP over stock?
Im sure 2-3 of those hp were due to the other mods, probably the Y-pipe specifically, but Id wager the manifold is 90% responsible. Comparing it to the stock CFI manifold its pretty clear that the GM engineers were making some not-totaly-perfomance-oriented choices. The ports on the renegade probably have close to twice the area. The really amazing part to me wasnt just the 37 hp gain, but that it can make over 180 rwhp from 3400 to 5100 rpm when the old one fell flat after 3800 or so.
E: Just remembered this motor has 1.6 roller rockers too. So probably 6% or so of the increase is due to the rockers, but it still never could run to such a high rpm without the manifold
Last edited by rorrapalooza; 10-16-2016 at 10:01 AM.
Nice and thanks for posting your dyno numbers. I have a question though. What did your A/F ratio look like on the high end WOT and how did it look all the way up? Was it going lean or dropping off? What FP are you running? I'd give it a bit more timing and see how it likes it. 198 at the wheels isn't bad at all for a relatively stock CF. I think 18% is maybe a tad high, but well within reason. Still not bad. Do you have a before, that would be the real test of gains. Also, do you have a way to monitor your FP while on the dyno? It would be interesting to see what the pressure was doing on high end. If it was dropping, so is your power, but you will also see that in the A/F going lean.
The dyno tech showed me the numbers, but unfortunately I didnt have the presence of mind to ask for a copy. I can tell you though that he remarked that the A/F ratio was "perfect" up to 5200. After that, he said it leaned out just slightly, not much though.
The fuel pressure is stock, never been touched, or checked, but I'd guess its around 12 psi given how well it ran. The fuel pump has been replaced, but it was with an 84 pump. Could be the replacement pump actually moves a little more fuel? maybe the hypertech chip helped?
a fuel pressure gauge was on the list of things to get if it leaned out on the dyno, maybe ill get one anyway though.
sadly no before dyno, its always been a strong puller but way stronger now.
Anyway, weren't you one of the guys involved with DCS?
This was actually one of the very first renegades shipped. Serial number 26!
sat around for the better part of a decade. Beautiful work.
My only complaint is that the hardware for the lid was a little short, but maybe thats my fault since I made my own gasket instead of using rtv.
I was thinking sometime soon I would try to drop in a hydraulic roller cam, maybe comp's extreme fuel injection 252, some AFR 180 cc heads with a compression ratio of 9.5:1 and a good set of headers, maybe even the ARH true dual system if I could stomach the price.
problem is, seems I'd probably have to get a totally different ECM to run that, and as far as I know DCS's HAM board isnt available anymore...
Any suggestion for how I could still run a similar set up?
the dyno tech said A/F ratio was perfect up until 5100 rpm and then it leaned out just a touch
I agree with Buccaneer about more timing and watching fuel pressure. however, if your A/F ratio didn't drop until 5100, your power was already on the way down. I'd blame it on the exhaust (mostly).
Unfortunately didn't find the time to play with the timing this weekend, but once I do, ill make sure to keep trying more till it pings. I've heard 12 degrees works nicely.
The dyno tech showed me the numbers, but unfortunately I didnt have the presence of mind to ask for a copy. I can tell you though that he remarked that the A/F ratio was "perfect" up to 5200. After that, he said it leaned out just slightly, not much though.
The fuel pressure is stock, never been touched, or checked, but I'd guess its around 12 psi given how well it ran. The fuel pump has been replaced, but it was with an 84 pump. Could be the replacement pump actually moves a little more fuel? maybe the hypertech chip helped?
a fuel pressure gauge was on the list of things to get if it leaned out on the dyno, maybe ill get one anyway though.
sadly no before dyno, its always been a strong puller but way stronger now.
Anyway, weren't you one of the guys involved with DCS?
This was actually one of the very first renegades shipped. Serial number 26!
sat around for the better part of a decade. Beautiful work.
My only complaint is that the hardware for the lid was a little short, but maybe thats my fault since I made my own gasket instead of using rtv.
I was thinking sometime soon I would try to drop in a hydraulic roller cam, maybe comp's extreme fuel injection 252, some AFR 180 cc heads with a compression ratio of 9.5:1 and a good set of headers, maybe even the ARH true dual system if I could stomach the price.
problem is, seems I'd probably have to get a totally different ECM to run that, and as far as I know DCS's HAM board isnt available anymore...
Any suggestion for how I could still run a similar set up?
Yep, one of the owners of DCS and thanks for your support, a lot of work went into that manifold. OK, too bad you didn't get a "before" pull. If you never checked the FP even after the pump change, I would do that so you know where it is, it may be on the edge and maybe adjust it just a tad more and be good. It should pull all the way to 5,500. Just a suggestion.
If you made your own gasket which isn't a bad thing, you may have run into issues with the top plate screws depending on gasket thickness, we only use sealant which works fine, just never use "the right stuff" black on the top plate unless you never want to remove it. As far as a HAM board is concerned, I have plenty of boards if you need one. Send me a PM when the time comes.
Not that it matters for power, but always thought the crossfire looked cool. Reminds me of the old cross ram intakes. Think thats what they were called.
cant wait to get the fuel pressure set up right too.
Sounds good and also sounds like it is pulling the entire way kind of, but it also appears that you cut it short? With just the dyno sheet to go by and it is a bit blurry to tell, it looks like you are going lean after about 4,200. You don't show the A/F so it makes it hard to tell, but the power curve kind of shows that by dropping off a lot after 4,200. To me, that is indicative of low FP or lower than it needs, that's why the A/F is so important to see. If this is true (lean), once adjusted it should pull all the way to 5,700 with no problem and not drop off...
the throttle was cut at 5400 rpm. I posted a scan of the dyno sheet at the top of the thread to make it a little more clear.
as far as sound goes, I found that flowmasters + a walker Y-pipe with crossover made for good exhaust note with minimal drone. Im thinking im gonna invest in the ARH true dual system next, mated up to the flowmasters... may be a bit louder.
the throttle was cut at 5400 rpm. I posted a scan of the dyno sheet at the top of the thread to make it a little more clear.
as far as sound goes, I found that flowmasters + a walker Y-pipe with crossover made for good exhaust note with minimal drone. Im thinking im gonna invest in the ARH true dual system next, mated up to the flowmasters... may be a bit louder.
The interesting thing to me is the big dip in tq and hp at 4200 rpm on the first pull, then moves up by 200 rpm and is less severe on the second pull, and then moves up farther and is much less severe on the 3rd
The dyno tech said it was probably just some sort of anomaly in the timing or something, but honestly its probably the first time this block has been revved past 4,200 since 1988. Could be something freeing itself up... the injectors cleaning themselves from flowing that much or something...
The interesting thing to me is the big dip in tq and hp at 4200 rpm on the first pull, then moves up by 200 rpm and is less severe on the second pull, and then moves up farther and is much less severe on the 3rd
The dyno tech said it was probably just some sort of anomaly in the timing or something, but honestly its probably the first time this block has been revved past 4,200 since 1988. Could be something freeing itself up... the injectors cleaning themselves from flowing that much or something...
Once you get the FPA on it and verify the FP is set where it needs to be, you need to watch the gauge while on the dyno. If it starts dropping FP after 4,200, the pump can not support the flow demand. If that is the case, replace with 87 vette pump and leave the FP where it was set before the replacement. Car will run like a different motor. Also check the pump filter and inline fuel filter on the frame rail.
10-14-2016, 09:59 PM
84 Crossfire Renegade Manifold Dynoed
Giv'er more and see how it likes it. 
