A cure for the raspy CDI blues

[treynor]

Just a quick update -- I'm continuing to mess with my car (natch) and one big positive change was adding Borla 3" straight-through side sill mufflers to my existing Belanger cat-back. This mod was recommended by both Borla and Hennessey, and it has made a HUGE difference in sound quality. The "mad squirrel" rasp is completely gone, and in its place is a quieter, much deeper rumble which is IMO a more pleasaing sound.

I'll get some video/audio footage of the new setup in about a week, after we get all the mud off the exterior and interior of the car... but that's a different story.

 

[WCKDVPR]

Ben,

I saw the swamp thing at Valaya this morning with some serious road racing slicks on it. What's the story, how did it run?

 

[treynor]

The car ran beautifully. I was out on the track passing people left & right, and lost the back end coming through the left bend which follows Riverside curve. I probably backed off the gas fractionally to tighten up my line, and the car (as it turns out) was set up rather loose. The back end came around, I wasn't able to catch it, so I went two feet in (i.e., clutch & brakes) and we spun off the track at ~80 mph, through the dirt, and into the only mud patch in the entire Bakersfield area. I have no idea why there's mud there, in the middle of August in 100+ heat, but there was and it sprayed through the open windows as we described a 180-degree spin in the mud patch. We ended up needing a tow from the local tractor, as the rescue vehicle almost got stuck trying to get to us.

Anyway, I cleaned everything up (including dismounting all four wheels and cleaning mud off the inside of the rims and the brake/suspension) and got back on the track later that day, but the slide through the mud had loosened up the oil return line from the crankcase breather, and I started losing oil pressure (i.e., below 30 psi but above red) after 4 laps and decided to call it a day rather than risk my motor.

Hopefully there's nothing more serious wrong than a clogged oil filter screen. OTOH, if I've damaged something, it's the opportunity to replace it with something better

Lessons:
1) tire pressure is critical. After my spin, I played a bit on the skidpad, and with only 1 PSI difference between front and rear tires I couldn't catch the back end when it came around. With 3 PSI difference it was child's play to catch the slides.
2) slides are harder to catch on slicks than on street tires. I've driven on slicks before (Russell Racing) but clearly need more practice before being entirely comfortable pushing their limits on a roadcourse.
3) 600 HP + 14" slicks + good brakes + good suspension = one hell of a roadcourse car. As an exercise in one of the sessions, I drove around in 4th gear (including the 40 mph corners) just to practice my lines. Even in that mode, I still ended up stuck behind M3s & Porsches, and had to pass them to avoid frustration. It's not that I'm such a terrific driver; the car is just a monster.

 

[99 R/T 10]

Hey Ben,
Were the Borla mufflers the Sportsmans?

Mike

 

[treynor]

Correct, the Borla Sportsman series. The Borla part # is 40085, and you'll naturally need one for each side. I ordered mine through Sean Roe.

 

[TorQ Junkie]

Ben,
1) Any way to get dB levels?
2) Do the Borlas reduce power that one may gain from high flow cats? In your present case, a few rWHP is a minor fraction of the total. For the rest of us with exhaust bolt-ons even 5 hp would be significant.
Thanks for the R&D saga.
Frank

 

[WCKDVPR]

Ben,

Sounds like you had a great time. Glad to hear you only got muddy. What tire temperatures did you find to work best? Also, any tips on set-up for those of us with minimal track experience?

Anyone with good road racing advice please jump in.

Thanks.

 

[Stephen Yap]

Ted, what did I tell you about treating your customers ??????

from,

a slow driver

 

[JonB]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by treynor:
........I'm continuing to mess with my car (natch) and one big positive change was adding Borla 3" straight-through side sill mufflers to my existing Belanger cat-back...... made a HUGE difference in sound quality. The "mad squirrel" rasp is completely gone, and in its place is a quieter, much deeper rumble..... <HR></BLOCKQUOTE>

BEN: Please clarify? Two customers of mine have read this thread as your dissatisfaction with the Belanger sound! Of course, they MISSED the earlier thread about the Archer-CDI headers actually causing the raspy-squirrel sound, and that you LOVED the Belanger Header and Cat-back sound pre-CDI/Archer.

Correct? "Ben Says" appropriately carries a lot of weight, and the above may have been mis-interpreted............

 

[treynor]

I should syndicate my new column, "Doctor Ben Recommends".

To answer various questions:
(1) I will be back on the dyno this Saturday to verify any HP gain or loss. I would expect zero HP loss after adding the Borla mufflers -- they're a 3" straight-through design, and they're aft of the catalytic converters.
(2) Ted, Bakersfield was mum but Buttonwillow called and said that, seeing as I've had two spectacular get-offs in two visits, I now qualify for a "frequent flier" discount on their picture T-shirts.
(3) I will take some dB readings both at idle and 70 mph cruise. I've got previous dB data to compare with -- yes, I measure and document *everything*
(4) Track setup -- it's going to depend on suspension setup, tire choice and aerodynamic aids, of course, but start out with several PSI higher in the front than in the rear. This will cause the car to push (understeer) and make it easy to recover from back-end slides. As you become comfortable with sliding & catching the rear, gradually change the setup (i.e., reduce front tire pressure, alter suspension) to balance out the front and rear traction. The closer to neutral, the faster you'll be able to go through corners, but the easier it will be to spin.
(4a) Important safety note -- it's much harder to catch slides on slicks than it is on street tires because their traction / slip angle curve is much steeper.
(5) Jon et. al., the Belangers had a wonderful deep rumbling sound which is still my favorite. After switching to the CDI headers (and swapping in Hennessey's higher-compression heads), that sound became a raspy "whaaaaa" at WOT. Adding the Borla side-sill mufflers has eliminated the rasp completely and changed the exhaust note to one which is quieter and higher-pitched than the Belanger, but considerably deeper than the CDIs without the side-sill mufflers.

In order of aural preference:
1) Belanger headers with Power Effects mufflers: deep, loud with PEs open and mellow with PEs closed.
2) Belanger headers with Belanger mufflers: deep, very loud.
3) CDI headers with Power Effects mufflers and Borla side-sill mufflers: nearly as deep as (1), very quiet with PEs closed, moderate volume with PEs open.
4) CDI headers with PE mufflers: moderately raspy & loud with PEs closed, very raspy and obnoxiously loud with PEs open.

 

[Martin D]

You know, at WOT on my car, I am not so sure I hear a raspy sound. It is certainly not a deep throaty sound.....but more like an INDY car. It sounds like all hell has broken loose. In fact, I had one guy tell me he heard me get on it and it sounded like a really bad a$$, ********** Sport bike turning 12000 rpm.

Does that sound like what you had Ben???

I have the Hennessey heads,headers and mufflers.

Regards,

 

[treynor]

Yep, that's about right Martin. I likened it to a Honda motor revving waaaAAAYYYY up, but a sportbike is another valid [and more flattering] comparison.

FWIW, a 10 cyl engine @ 6,000 RPM makes the same pitch note as a 4 cyl engine @ 15,000 RPM