Glimmer

Saturday, I took my car to the strip for the first time with new converter. I wasnīt that pleased with the times. My best lap was the first!?! 9.325@75.125 / 14.657@91.597. Didnīt get the 60īs below 2.114

The best time with stock converter was 9.374@75.7

My setup (L98):
- stock bottom (rebuilt)
- HSR with AFPR (tried from 41 to 51 psi)
- 991īheads from -69 (supposed to be ported, milled and 3-angle cut)
- cam Bullet Racing with stock pushrods and lifter (dur@050 220/225, lift 510/525 LS112)
- Ford Racing SVO#24
- MSD 6AL + Pro Billet distr.
- Edelbrock TES
- 3" race catalyst
- Wells MAF

TH700 with TCI Streetfighter and TransGo
- B&M TorkMaster 2400
- B&M Console Mega Shifter
- Stock 3.27 9-bolt rear

The car wonīt pull enough on 3rd gear and donīt rev more than 5.700rpm. Shifting is around 5.500.

Iīm running base timing @ 10deg. without knockīs and tried the ARAP chip (also with base timing corrected) but no results. It seems that the best chip is ARAP with the timing lowered a bit. I also get some exhaust detonation that I canīt get rid of. It comes whatever chip Iīm using.

What could be my problem? Iīm using stock suspension.

/Andreas

Damon

Coupla things:

Valve springs? Stock springs don't stand a chance at controlling that cam over 5000. Gotta have the RIGHT springs installed at the RIGHT installed height to get the most out of that cam. And that's a lot of lift for ANY stock head, unless the guides have been machined down to prevent binding the valve train. I'm sure you could go into a little more detail about the heads and what's been done (or not done) to them.

TPI intake. It's a strangulation machine over 4500 RPMs. In short, I think your cam is too aggressive for a stock TPI intake. You're giving away torque on the bottom end with the large duration but just when the cam start to "breathe" the TPI intake start to choke it off. Net net, you go slower.

Last, 24# SVO injectors are really equivalent to about 26# injectors in GM's rating system. Ford rates at 37#, GM at 42# pressure. A stock chip (even the ARAP BIN) is built for stock 22# GM injectors. You might try either backign the fuel pressure down some (you might try 35-37# for starters and see how that works) or, more to the point, a custom chip is gonna work much better than stock programming when you've got a cam that's nowhere near stock any more.

krazzycowgirl

I didnt see anything about a sway bar or panhandle bar.


Also What tires are you using?

Glimmer

Iīm not running stock TPI, I wrote HSR with AFPR. I donīt have either new torque-arm, sway-bar or other kind, just stock WS6 suspension.

The tires are BF Goodrich Dragradial 255/50-16. I found out that the best traction were to drop pressure to 15psi.

I bought the heads from a company in Massachussets. It is casting 991 and this is from their invoice:
- Stainless Steel High-Flow Valves
- High Performance Springs (0.55")
- Comp. Cams Heavy Duty Racing Spring Retainers
- Comp. Cams Heavy Duty Valve Locks
- Comp. Cams Valve Seals
- 3-Angle Valve Job
- Mill heads
- Stage 2/3 Portwork

Intake is 1.94 but I donīt know the exhaust.

As for the chip, Iīve tried to set the inj.constant from 24 up to 27. Only difference I found, was that I got slightly better BLM readings, but it still says itīs too rich.

angel71rs

The only 991 listed on mortec I could see is for a 75cc low performance head made from 72-73. That is part of the problem. The larger chamber of the heads dropped your compression about 1 full point. I see the heads were milled, but unless they took a massive chop, the chambers are probably still big. Low compression is made worse by a cam with longer duration that bleeds off low speed cylinder pressure. You could probably run 14deg timing and it wouldn't ping, and it would probably help with low compression and bigger cam.

Check full casting number to confirm head cc's:

http://www.mortec.com/castnum.htm

Glimmer

Hmm. The heads are stamped with 69.

Iīm getting so pissed. I turn to a company asking for a set of heads to match my specs. They new about everything, even got my intake to portmatch (witch it turned out they havenīt done ). What happens? They F#%K me up, as I live across the god damn Atlantic.

Glimmer

Do You think the heads would do if milled down some? Or am I in to buying a new set?

angel71rs

I don't know if the heads would take the big chop needed to get the chambers small enough to get compression back to where it was before. Even if it did, the intake manifold would have to be machined so that it would bolt on. Big cuts off the bottom of heads, or the block deck, lower the heads so the manifold angle no longer matches.

Did you verify the full casting # on mortec? If they are 75cc heads. There are companies that have no problem telling you whatever they want just to get your money. That is why boards like this are such a great asset. You can get the facts here.

Where are the heads stamped 69? There will be a casting date in the rocker area that will have a letter for the month and two numbers for the date.

BigCasino87GTA

Aside from going over the heads, I would go for a larger TB and also re-adjust the timing to about 8 degrees or so.

Glimmer

Angel71rs--> Didnīt think about the angle. Thanks for enlighten me. Darn, so Iīll have to go with new heads.

BigCasino--> Iīll have my stock TB bore to 52mm in a week or so (when a friend of mine is back from vacation), but is really necessary? Wouldnīt a 48mm flow enough up to like 500? Thatīs what Iīve heard. Iīll go up to the car in the evening to re-adjust the basetiming. Should go all the way back to 6, or is 8 good?

There is not great of room behind the HSR, and my patience is going down quick fast now. The worst thing, is that Iīve mailed the company that did the heads for me, and they donīt even deny anything, they just say that my engine needs to be blueprinted to work with the heads (just because they have been in the buisiness for over 35 years).

Thankīs for helping me guys.

BigCasino87GTA

You're right, the stock 48mm is good up to 500 horse, I'll try to think before I type next time
About the timing, yep - 8 degrees.
I know these are small mods, but have looked into CAI, K&N and a an airfoil? These will help your engine breathe a little better. While I wouldn't expect a dramatic horsepower gain, every little bit helps. I didn't notice anything about an exhaust system in your posts ( except for the high flow converter ), headers, cat back and such.

Glimmer

Oh, sorry. Iīve done my own CAI with open BMC filter, and a Airfoil is placed in the TB. Iīve done all the minor mods there is.

Edelbrock TES "headers" >-- 3" race catalyst -- stock 2 3/4" back.

Iīve started looking for some Edelbrock Performer RPM heads. Guess this would do better than these darn 991īs. Is there any other valueble heads to go with instead?

Angel71rs: Hereīs a picture of one side of the heads http://hem.bredband.net/b123938/heads.jpg

angel71rs

I couldn't see clearly enough when I zoomed in on the casting #'s. The 7 digit # under the big "T" is the actual casting # you would look up on mortec. The numbers under the clock symbol are the date codes.

As I said, if it is big chamber, your compression would be low. So I would recommend 12-14 deg initial timing to help with low speed torque. Just make sure it doesn't go over 36 total at high rpm.

While the heads are not ideal for your combination, I think your mph should be much higher than 91. A completely stock L98 can run 93-94 mph in the quarter. With your improvements, you should be around 98-99 mph. So for now, optimizing your combination should get you low 14's or maybe into the high 13's. With a good set of heads, about 4 or 5 tenths quicker.

One thing on the converter. My nephew had a 454 Chevelle with a B&M 2,400 converter & a TH400. It shifted mushy and turned too much rpm per mph. I told him as a low buck test to go pick up a rebuilt Corvette 6 lug torque converter from the transmission supply house. Cost: $35. These converters have a little higher stall than regular converters, but are stronger due to original Corvette application.

The car improved immediately. The rpm in the lights dropped by 700 rpm! Et dropped 3 tenths. I don't know if it was a defective unit, or just not right for his application. At 91 you should be turning around 3,800 in third. BTW, he left the $35 dollar converter in the car.

Also, the 3.27 might have been good with the stock L98, but with your bigger cam, lower compression, and HSR all reducing torque, it might no longer be ideal. Something along the lines of 3.73's would help a lot.

My point is that it could be a combination of things that are keeping your car from running the way you would hope it would with all that you have invested in it.

Rage

14.6 on a Stealth Ram L98??????Good grief, a bone stock L98 will turn those numbers....I dont know what tha problem is, but tell me when you figure it out so I dont make the same mistake.

87camracer

another thing that no one has mentioned is your headers and exhaust choices. the stock catback is one of the worst made not to mention you are going from 3inch outta the motor to 2 3/4 inch further back? get a new 3 inch catback and that should help a bit. also you didnt say what y pipe you are running so i would assume stock? also the headers are some of the worst headers made. ive read on thirdgen.org that the TES headers in some cases are actually worse than the stock manifolds. might look into that too.

as far as my car, my best is a 14.53@93 with a 1.9 60 ft on street tires. thats with the stock TPI intake, a CAI, MSD coil, 3 inch catback with 3 inch cutout, and a tranny with a vette 2200 stall, some unknown POS shift kit, vette servo and stock 3.23 gears.