Latest Project - Headers

[Yargk]

I'm assuming the amount of air moving is related to hp. So at what number `should` you jump up to 1.625 and at what number is 1.5 truly too small.

[RarlyL8]

1.5" will support at least 500WHP.

[Yargk]

Cool, so I know I'll get the 1.5s since my ultimate long term goals are less than 500 whp. btw yesterday I started pouring through the forum looking for header information. I checked out shorties and custom equal length systems from a number of sources as well as of course the stock setup. The more I looked, the better your headers looked. I won't repeat all the positive details I ended up noticing, because I think others have already found them. I'll simply say I was impressed by how well thought out the design was. Of course the workmanship speaks for itself.

I understand now how foreign made shorties would be annoying to compete with. Your headers are superior in every way. However, those shorties seem to perform well, almost despite the simplistic design, which to me means that all the heuristics we think we know about header design aren't enough to work on alone. Thorough testing is required. That's the only reason I would prefer a direct comparison. Otherwise what I'm doing is comparing your gain vs. the 44 hp B and B claimed gain after subtracting what their muffler might make since you used a sport muffler in both tests. Fabspeed also claims 46 hp, so these numbers seem to make sense for muffler + headers (fabspeed included an intake which might add 0-5 hp). My own testing of a GHL system a long time ago echoes these results. Of course you have a better turbo and intercooler so a set of headers should add a bit more power on your car than a bone stock car.

Anyway, great work.

[RarlyL8]

Those 45HP claims were made against stock engines of what configuration? The true "stock" benchmark must be the 300HP Euro. That engine configuration remained unchanged for the entire run of the 930. The US versions were all choked off and/or detuned. Not until the 964T did the US cars breach 300HP.
I use the most common mild mods for a baseline engine, including the Euro exhaust, as this gives the best info to enthusiasts.

[Yargk]

Yes, I most of the 45 hp claims are against the US early headers. I'm pretty sure the fabspeed claim was on an 87, which has the late headers, but I could be wrong.

Regardless, if you're making 350 whp on .75 bar, you have probably the most efficient non-custom headers in the business. Wouldn't this be 400 whp at 1.0 bar?

[torresmd]

I cannot wait to get my headers! I am so excited to try these out.

[RarlyL8]

Your headers shipped out at 8:00 this morning Steve.

In theory 0.25bar (1.0-0.75) would add ~38HP. I think that might be optimisic given I have stock heads and a K27-7200. If I had ported heads and a K27HF that would support the flow needed to sustain 1.0bar @ 6000rpm then the 38HP would be reality.
That brings up a good point about bench racing; all mods must work together or the theory goes out the window. Using that same logic I assume that you would not see a 50HP increase using my headers (or anyone else's) if bolted on a bone stock 300HP Euro engine. The 3LDZ and stock muffler would not allow the flow needed to support the power potential of the headers. The system would not be optimally balanced.

[Yargk]

How do you calculate the 38 hp number? (naively, I thought it would be more.)

[RarlyL8]

Conservative rule of thumb 15HP/0.1bar (0.25) = 37.5HP

[RarlyL8]

Went for a drive today to record some data. I'm getting more used to the headers and noticing more things. One is boost threshold and full boost. The boost threshold with my K27-7200 was reduced from ~2500rpm to <2000rpm. Today I noticed a consistant 2200rpm threshold in 5th gear. I noted that reading and went back to the shop to do some intercooler work. Well when I pulled the intercooler I found what is pictured below. The O-ring had blown out the side of the up-pipe and half of it was laying on the distributor! No telling when this happened so I need to verify all previous data. I also had to fix the threaded stud that secures the intercooler to the fan housing as it had pulled out of the B&B intercooler - stripped threads. Arrrg!

[gogomobil]

I had the same issue two times on my car, fitting that O-ring correctly is pure headache...

[RarlyL8]

I figure that the stud that attaches to the fan housing bracket was likely stripped all along and me taking the intercooler off and on 50 dozen times finally caused the failure. The intercooler was pushed up off of the turbo up-pipe as far as it could go which was enough to allow the O-ring to be pushed out the back side. I'm thinking that I hit boost hard and it popped up and then I let off abruptly and all the stretched intercooler rubber bushing slammed it back down on the O-ring which sliced it in two.
I'm going to safety wire it today as I cannot have any more delays. One thing's for sure, this thing runs like a Banshi! Not stupid fast yet but quick enough to demand your full attention.

[28rusblue]

I finally got my RarleyL8 headers and exhaust fitted.

I have a stock 1978 930 ROW car which had the factory exhaust. Amazing the difference, the car now has more low end torque, making it more drivable in heavy traffic. The boost comes on earlier and the car seems to build more boost pressure at a much quicker rate, accelerating much quicker.

No drone, but awesome crackle on deceleration, yet still is quiet enough to sneak past the constabulary on the way to work (with no boost), and a much more well, 'aggressive' sound...

Amazing the difference on my car, significant bolt on HP....

[RarlyL8]

Thank you Greg. They do wake up when you tune the exhaust and relieve the back pressure!

[RarlyL8]

I received this note recently and would like to share it with those looking for information on how my system stacks up against the competition. There are now a few sets installed that have replaced short tube headers with great results. The set of RarlyL8 930 headers in the testimonial below replaced a set of SSI equal length long tube headers. The results speak for themselves.

Brian,
You sir, are a Maestro!! I had no idea a 930 could sound so good! I am in awe. I just got back from the first drive after bolting them on, I ended up driving around for two hours. My wife finally had to call to make sure I wasn't broken down somewhere. Alright I'm done. The performance was better than I had anticipated, the boost seemed to come on slightly sooner probably just a bit over 2k rpm, but it really enhanced the upper range. It hit really hard at 3k and just kept pushing! Before, the turbo kind of fizzled out above 5k. Not anymore! I did not really go much beyond that, as I would like to verify that my afrs are all in order before I push it too hard. I don't know if I mentioned it, but I have a K27S installed, and it seems to be a great match for these headers. Again Brian, superb work! I am really going to enjoy these, and I have zero regrets replacing a fine set of SSIs for these.
Sincerely,
Eric

[steven c]

Brian,

When will the 965's be ready?

[e170drvr]

Hi guys,
in addition to my above note to Brian. I would also like to point out that these were extremely easy to install, everything fit perfect. This design allows adjustment on every axis for a perfect fit with zero leak. I was on the fence for quite a while on ordering these since I had a very nice SSI setup installed, again Brian's work, but I am absolutely delighted with these. I have no dyno data, but seat of pants meter is telling me I have more power and the upper range has been significantly enhanced, my turbo doesn't seem to run out of breath. The sound is heavenly, fairly quiet at low rpm but perfect WOT on boost very sophisticated "tuned" sound. If someone could get a good sound clip on these, Brian would be real busy on just the sound quality alone. Along with the above, the fact that I recieved my headers and muffler 2 days after I ordered them, made me one happy customer.
Eric

[RarlyL8]

Thanks Eric, I hope you didn't mind me posting your email. It includes some good info that some folks have asked about. I can tell them these things but it is better when the experience is shared by a fellow enthusiast.
The sound is tuned with a very smooth pitch and absolutely zero resonnance at any RPM. I absolutely love it. Ferrari like?

Steven, these headers will fit the 964T as well. I've got a set going on one here shortly so maybe that fellow can chime in with his thoughts.

[930_pit]

We just installed this headers last week and this is the best upgrade I have so far. My car is like transformed to new car - better acceleration and the boost is so exciting. Whenever I drive my car, it’s always all smiles now. Thanks to Brian for a very great product!!!


Arlon

[steven c]

Originally Posted by RarlyL8

Steven, these headers will fit the 964T as well. I've got a set going on one here shortly so maybe that fellow can chime in with his thoughts.

With a Cat and the stock exhaust piping? I have a muffler bypass and Strosek tips I want to keep and I need a cat so my wife will ride with me. She doesn't like the smell of unburnt fuel!