930 Headers

[78P930]

What kind of horsepower gain could I expect from a good set of headers replacing a Euro style exhaust(no cat)? Also, manufacturers are considered to produce a superior product?

Pat

[dyerkes]

You really won't gain much, if anything if you already have a Euro exhaust as that is what the aftermarket headers are designed after (the right bank crosses over to the turbo up-pipe at the bumper side, instead of at the transmission end of the crankcase as the US models were designed).

David
1986 911 Turbo

[Dave 86 930 Fl]

Pat,

I'm not sure of the exact hp gains from my B&B headers, but my car dyno'd at 421 flywheel hp (360 rwhp). Headers made a huge difference in turbo lag and the car sounds great. As a far as bang for the buck, headers are high on my list.

[78P930]

David, If the euro exhaust crosses at the rear, I guess I don't have it. Mine crosses at the transmission.

Dave, Those are impressive numbers, were you using the stock cam? Did you actually run on the dyno before and after installation( would help put to rest the wild speculation over drivetrain loss)? I just put in a K27-7200 and SC cams and pulled 290 RWHP at 0.9. By the way, what is EBC?

[dyerkes]

Pat,

If your car does have the US version of the headers (cross-over of the right bank occurs on the transmission end of the engine), than you stand to loose about 40lbs and decrease your spool time by about 700rpms. Dave's gains could only have occurred with a number of mods on top of the headers - cams, free-flow muffler, and higher output turbo. Once you start increasing the HP of your turbo, you better do two things: get a more efficient intercooler (no HP gains, just keeps the charge temps at a reasonable level) and (2) at a minimum, have your AFR settings check to make sure that you aren't running lean with the improved flow that you created with the previously mentioned mods - ultimately (if you decide to stay CIS) you should consider having your fuel head modified by Stephen Kaspar of IA, so that it can provide enough fuel flow at the top end. Don't forget that the stock rod bolts are only rated to the mid 400 HP range, so if you decide to do a significant number of mods you may need to consider having to replace these in your HP equation.

I have first-hand experience with this as I am currently in the process of rebuilding my motor and performing some major upgrades to it.

Good luck!
David
1986 911 Turbo

[89turbocabmike]

Originally posted by 78P930
David, If the euro exhaust crosses at the rear, I guess I don't have it. Mine crosses at the transmission.

Dave, Those are impressive numbers, were you using the stock cam? Did you actually run on the dyno before and after installation( would help put to rest the wild speculation over drivetrain loss)? I just put in a K27-7200 and SC cams and pulled 290 RWHP at 0.9. By the way, what is EBC?

Pat, you do have a euro exhaust. The euro exhaust has the right bank cross over pipe at the transmission and was later adopted to US turbos when reintroduced to our market. The difference being that US models had a cat/muffler combo after the turbo and euro's just had a muffler. The early us models (76-80)had thermal reactors and actually connected/crossed at the rear but were highly restrictive even when the reactors were replaced. Besides being about 20 lbs lighter(behind the rear axle, think weight distribution) you will experience even quicker spool and not experience a net hp increase, but will have it some 500-800 rpm sooner. Headers will increase drivability more than any other bolt on mod. Regarding dyno #, I wouldn't get too concerned. Dyno figures vary wildly depending on dyno type/brand, software parameters and operator. I could put your car on a dyno and get you just about any hp reading you want The main thing is to find a good dyno/operator so that you can make comparisons mod to mod. BTW, EBC is Electronic Boost Control, a fun toy and in some cases an important tool but best just to stay with your .9 spring at this point in the learning curve

[78P930]

Headers, it is, then. One more question concerning the fuel head mod. If the A/F is checked and doesn't lean out, is there any reason to make the modification or is there any other way to accomplish the same thing?

Thanks to all for your input.
Pat

[89turbocabmike]

With your current set-up, 7200/sc cams, the fuel head mod is unnecessary. You really shouldn't need it unless you go with a bigger turbo such as the k27-high flow, or a k29. I run a k27-7006 with plenty of fuel to spare, but had a k29 hybrid that was on the edge with the stock fuel head. There are the rice/andial fuel enrichment units, but I think if you need more fuel the head mod is better and priced comparably. If you don't have a bigger than stock Intercooler, that should be a next step.

[78P930]

Thanks Mike. I have put on a B&B IC. I question its effectiveness as it sits, until I can fab up a shroud to focus airflow through, instead of around the cooler.