Yea its got a hood mounted gauge was seeing 6 to 7 thru traps have it set at 8 at idle. That's where the taller tire idea came from maybe it's just lay down a little due to just hanging its tongue out just a little to hard not sure lots of testing to do, that's always been my fear wearing out a engine testing and tuning to find optimum and then not getting to enjoy optimum for long ha
Your 1.44 60 foot is the same as my car ran back in '96 at the Nationals. The car weighed in at 3770 so that was close also. My heads are a the T/A experimental version of the TE heads, and I run the SP2. At the time front suspension was stock with global west bushings, no sway bar. Rear had Global West lowers with Art Morrison uppers that had 3-way upper mount locators, factory 7/8" rear sway bar. Koni's all around. Found an old time slip, don't laugh though I must have been asleep at the lights, car #341. :sleep:I agree with Jim your MPH is off.
Be careful here.. first off, 6-7 thru the traps raises a red flag.. that's too much.. so immediately I suspect there is an issue. Only a 1 psi drop would not at all be normal. In my experience it's typically 3-4 lbs.. with a good pump, good line sizes, and a return style regulator, and big needle/seats in the carb.. Keep in mind that where your picking up the fuel pressure, and the pressure at the needle and seat, very well might not be the same. For a totally illegal, but useful test.. get a fitting that jumps right in place in front of one of your carb lines, and tap in decent quality vacuum pressure gauge.. run the line out of from under the hood, and tape the gauge to the windshield.. insure that both gauges stay the same.. sneak it out on a county road.. That will eliminate everything up to the needle/seat..I have seen plenty of regulators that show a good pressure at the pressure pickup point, but can't flow enough volume thru them for the demand. This will fool you every time. After that you have to look at O2 readings to insure that the fuel is keeping the bowl full, flowing correctly thru the carb and getting burned in the engine. I hammer on this now, because you have to be sure.. engine damage is very possible if your running it lean, and your describing a textbook example of fuel system issues in a drag car. Not to mention all the other testing is pointless, if your running the bowls low.. The engine will "sound" fine, just will be missing 30 or so HP. My own experience with a similar car, with less HP and more weight, yielded good air times of 11.19 at 119mph, with a 1.50 60' You have at least 50 more HP (I had street/strip ported iron STG 1's- 260 cfm) and you have 300+ pounds less weight. Once you establish that your fuel delivery is adequate, then I would look at the converter, and do the math with your MPH/tires size and trap rpm. Good luck JW
Hugger, Your MPH, ET and weight are very similar to those of my convertible. You have more cam (250ish for me), more carb (QJet for me), and more gear (3.73 for me), but I probably have better flowing heads. If you are looking for something "major" to upgrade, then I'd suggest either getting your heads on a flow bench or a hydraulic roller cam, or both. If you are interested in getting the most out of your combination in its current form, then you have gotten a lot of really good advice so far.
Yea, this power plant isn't coming out unless it's has to for repairs I assure you , poor car has been down enough over the past 4years
So are you saying that you should have pressure drop at the traps ??? I have 0 psi drop thought the the whole run
Liquid filled gauge taking off at the regulator welden pump and Reg , pump is rated for 1200 N/A never had it drop
I pull off my Aeromotive Regulator psi port also with a BG gauge on the fuel log at carb it and hood gauge seem to coincide with each other at idle anyway
Jim- A couple of questions here. How can 3-4 lbs drop on a typically 7-8 lb carbureted system be OK, if you're worried about leaning it out. Wouldn't the 3-4 lbs tend to possibly create a lean condition? I thought the entire purpose of larger fuel pumps like the A1000 were to prevent the 3-4 lb drop off?
4 psi showing on the gauge, means the needle and seat are not wide open all the time.. so the bowl is full. 2psi often can mean that is the pressure due to the restriction of the needle/seat, so 4 is often mentioned as "minimum fuel pressure at WOT in the traps". There would be no difference between 4 psi at WOT vs 8... full is full, another 4 psi on the needle and seat means nothing. The purpose of fuel system is to keep the carb bowls full at all times. And of course, higher HP motors use more fuel, and faster cars exert considerable G force against the flow of the fuel column.. the larger the feed line, the higher this pressure against fuel flow, will be. Assuming of course, that the fuel tank is in the rear of the car, motor in front. That is, btw, the reason most real serious race cars have the fuel tank in front of the engine. I have never worked with a system in a car that set pressure at idle and WOT pressure is the same.. it is possible, we see that on the dyno, but that has a monster fuel system on it, good to 1200 HP on Methanol (twice the volume of gasoline).. and it's stationary, and has a regulator with a large orifice. Usually, what we see is a 3-4 psi drop, when the system is flowing fuel at large volumes.. and typically it's not the pump, but the restriction to flow is the orifice in the fuel pressure regulator. That in addition to the G forces working against the fuel column. I suppose it is possible with a killer pump, and large orifice fuel pressure regulator, you could show "idle set pressure" at WOT, I just have never seen it. The important point is 4 psi minimum at WOT, in the traps, and the pressure tap on a fuel log is exactly the right place to measure this pressure. That will show you actual pressure available on the needle/seat, after all the lines and other restrictions. JW
Any car I have work with I never like to see a drop of more than 11/2 psi even that I would care for But back to main thread I would guess the car is running out of motor at that rpm my motor is same trap rpm but I have CNC ported S3 heads flow +370 I use 315 MT they the best tire I ever raced on I have a 12" rim run 18 psi hooks hard and drives great in the wind or what ever try the tire to get rpm down
I think I am gonna go with either the 315s or some of the Pro Bracket 29.5 Radials . I'm gonna be putting them on some Holeshot wheels that's the plan anyway. And use my Heavy torque thrust and tired 325s for street duty. Gathering up suspension stuff now then its on to the rolling stock and some brake upgrades I had a hell of a time getting it stopped for some reason
My thoughts are that 1 of several Rule of thumbs when building a fuel system is to have a system that will not drop at the carb. Its said and has been documented by several company's that a fuel system needs 8psi for every 1 G force on launch. So if you have a car that 60ft's 1.30 you will see approx 2.20 G's so the fuel pump will have to be able to pump a min of 18+psi. Don't quote me but for example I think the a1000 is 60psi. There are many things that can cause lean conditions in a given fuel system/build. There are a lot of people with incorrect fuel systems out there.
The 29.5 pro radials are nice and may fit better the 315 are a big tire on a 12" rim there 14" wide not sure if they'll fit on a 10" rim on a stock wheel well
Yea I was looking at the actual measurements today. I'm set on the Pro Brackets, talk to few local guys and they all agreed they work exceptional on Iffy tracks
