Re: to all 85-92 efi racers
 

Those 307" Olds had different secondary metering rods also, no "power step". They all came with the same secondary jets, you only change the rods on that end. Changing the secondary rods and removing that stop really woke that engine up. When I see somebody racing one I think "I'll bet it has the wrong carb". Should be illegal to do that unless they factor it hard enough. Like turning up the boost.

Sorry, just had to say that. :-)

Re: to all 85-92 efi racers
 

Since my name was posted up on pg7, I'll throw my $0.02 in here at the end - with a turbo car, more boost only makes more power to a point.

1st - Just like with a carb, the size of the turbo inlet determines the maximum amount of air you can flow. Airflow = power. And, just like with a carb, only the atmosphere pushes air INTO the turbo. Turbo cars must run a completely stock turbo - and tech DOES check it thoroughly. As me how I know.

2nd - There's a 'sweet spot' on every turbo that flows the most air and therefore makes the most power. Any more boost only raises the air temperature, it won't flow any more air. It's related to #1 above. My car goes faster at 14psi than it does at 24psi, and 24psi tends to break stuff (like pistons - again, ask me how I know) becasue the intake temp is so dang hot.

Re: to all 85-92 efi racers
 

Good point. My AF/S Shelby Z with the intercooled 2.2L seemed best at 20 PSI which is only 6 PSI over stock. I also went thru 3 sets of pistons and 3 new heads on my learning curve. But enough fuel with 20 PSI & C-16 kept it all together for 13.26 record. I wonder what would have happened with an aftermarket cam and headers? :D

Re: to all 85-92 efi racers
 

Rob and Jeff. Thanks for your informative posts. That scenario is probably the norm in Stock, but I'd bet that nobody qualifies #1 with stock amounts of boost. What do you think?

Bill

Re: to all 85-92 efi racers
 

I don't think anybody qualifies number 1 with a stock amount of airflow period. Whether under pressure or N/A.
Bill you fail to realize that nobody using a turbo fwd car in stock has a "stocker" head They use plain factory heads with a valve job,

Re: to all 85-92 efi racers
 

Art,

What would prevent a turbo car from running a head with the same sort of modifications that I'm assuming you mean when you say "Stocker head"?

Aren't the rules the same?

On the other hand, if you can run increased boost, why would you NEED "enhanced flow" (short-side radius mods, acid-porting, etc.) when you can cram it in there, regardless?

Then again, if you had BOTH.... :)

Bill, just wondering...

One question: Since you got me straightened out RE NEON heads, and valves, is your new race car the SOHC model (engine)????

Re: to all 85-92 efi racers
 

Bill -

I think Art is trying to communicate that increasing the efficiency of the ports is not productive since the head flows more than the inlet side of the turbo without any work.

Re: to all 85-92 efi racers
 

My 1.688 under run should've been more like a 14.0x instead of a 13.86. The boost was set to 13.5 psi (still not stock boost, I'll admit). Lot of good it does when the wastegate siezes, though. I was running CFS that weekend, I think I might have been good for #1 if it had run what I intended. Though, Polhill was right behind me, as I recall, with the Escort (a non-turbo FWD car).

Re: to all 85-92 efi racers
 

The point I was getting at is, the turbo cars do it with boost very cheap and effective. It seems like you and some other racers are jealous that they have to spend upwards of $5000 to achieve what a slight adjustment does on a turbo car.
If you think head flow doesn't make a difference. Retake horsepower 101. The srt4 motor has a turbo half the size of the early mopars. and it makes over 50% more horsepower. The early turbo cars are out of flow because of the cam/head below 6000 rpm. You can put 40 pounds of boost to it and it ain't going to flow much more. Boost basicly only effects the intake not the exhaust. You still have to get rid of what you cram in there.
As far as my motor goes, One reason is you can't get a cam over .410 lift in a sohc head. Plus the fact with the dohc that I can change valve overlap with out sending the cam back.
Now maybe thats an unfair advantage. OOOPS I forgot they don't even check overlap in a stocker, let alone a modified motor.

Re: to all 85-92 efi racers
 

Art Leong said, "The point I was getting at is, the turbo cars do it with boost very cheap and effective." in relation to getting sufficient air flow on the intake side, without expensive cylinder head modifications.

Thank you, Art!!!

FINALLY, someone with more than a modicum of knowledge, and with a lot of common sense, has agreed, in principle, with my ORIGINAL CONTENTION. which was that limiting the boost on turbocharged cars to their OEM boost spec (through the use of telltale gauge monitoring by NHRA) might could solve the problem of having two or three percent of the cars at national events (turbocharged cars) nailing down over fifteen percent of the #1 qualifying slots, as has been the case annually, for the last four years.

Without the boost levels they're currently able to run, they'd likely not be turning e.t.'s so far under their respective indexes.

I seem to be the only human being on earth who sees this as a problem, however, so I will no longer beat what seems to be a very dead horse, by now.

But, I think Art just validated my simplistic, but direct, line of reasoning about how this happens, with his explanation of why acid-ported (or, whatever) heads are not needed with a turbo.

Thanks, again, Art... that was a VERY well-writtten and interesting explanation, especially the part about the SRT-4 turbo motor.