- Oct 21, 2006
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Whoops! Typo. 4000 RPMS lolYour launch rpm is suspect
I've launched my lawnmower higher than that
Horse Power Gains?
- Thread starter 93gtmustang
- Start date
- Oct 21, 2006
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I have 3.55:1 gears, and I had to launch it at 6000rpms to keep it from bogging.
Kurt
Kurt
- Oct 21, 2006
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I had 3:73 with the original T-5 with 3:35 1st gear and it was a perfect combo. Then I bought a Tremec T-5z which has a 2:95 1st gear and it bogged badly. I have 4:30's now and it launches great. Wish I had gone with 4:10's due to the high rpms I have going through the traps. Close to fuel shut off.
My first gear ration is a 3.13:1 if I remember right. You want it to be high in the RPMs going through the traps. That's what makes it fast.
Kurt
- Oct 21, 2006
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Weight reduction. 13.1-13.3 was full weight car when I owned it. When I bought back my car the previous owner he put a fiberglass hood and skinny front tires on. I ran 12.953 with it this July like that.
Then I took the rear and passenger seats out.
Now its 12.6's.
- Oct 21, 2006
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So at 345 flywheel horsepower the 24 lb. injectors are performing at 90% duty cycle.
Should I go up to 30 lb. to meet the 85% duty cycle? Technically I would need a 25.37 lb injectors to meet the 85% duty cycle, so the next size up is 30lb.
Should I go up to 30 lb. to meet the 85% duty cycle? Technically I would need a 25.37 lb injectors to meet the 85% duty cycle, so the next size up is 30lb.
Fwiw I never install anything smaller than a deka 60lb injector for boosted cars.
NA stuff I like to swap the clips and use the LU47 injectors
NA stuff I like to swap the clips and use the LU47 injectors
WhiteCobra95
10 Year Member
- May 2, 2006
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The other option is to bump the fuel pressure a little bit to make the 24's flow a bit more. Then you would need to update the calibration for the improved flow rate and potentially a small shift in the injector offset time. But if you're planning on any additional engine mods that promote increased air flow, bumping the size up to have room to grow is probably the best path.
- Oct 21, 2006
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My fuel pressure is at 42-43 psi with vac hose off. That's what I had found works best with the set up. I just don't want to spend money if I don't have too.
I've been running the 24's for quite a long time and no problems. I was just messing around with the calculations and found I was a little short.
So am I ok too stick with the 24's?
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- Oct 21, 2006
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Makes sense. I don't plan on modding this engine though. It's simple and works great for bracket racing.
Thanks!
My question is what rpm range are you running or planning to run? If your calculations for 90% duty cycle are at 6000 rpm but you normally run no higher than 5500 or higher for only a blip, I wouldn't be worried.
What do you AFRs look like at 90%.
What do you AFRs look like at 90%.
- Oct 21, 2006
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Shift at 5800 rpms. Trap rpm is 6200. Close to the fuel shut off. My tach stores the highest rpm.
I just used the Ford Racing calculator to get a rough idea. https://performanceparts.ford.com/download/pdfs/ProperlySelectingEFIComp.pdf
AFR's? Air fuel ratio right? Im running the stock computer and don't have any equipment to get that info.
Thanks!
- Oct 21, 2006
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Bracket racing is all about experimenting, try bigger injectors to see if you get faster but honestly I doubt you'll see a change.
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I'm not loolking to go faster with 30 lbs. I just found that the 24 's weren't within the reccomended 85% duty cycle at my horsepower. That's why I'm here asking the experts here! I've raced the car for years like this with absolutely no problems. 5.0 stock bottom end, heads , cam and intake. No complaints whatsoever.
I really don't want to through money at it with injectors etc... if its fine like it is. When the time comes if I want to go faster, I'll get a race engine or a different car that's all set up. This car can be put back to street pretty easy the way it is, which is a good selling point if I decide to.
Thanks!
WhiteCobra95
10 Year Member
- May 2, 2006
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Add a wideband O2 and log your AFR / Lambda. That will tell you if the injectors getting close to saturation is a problem. If you see a hard lean shift over rpm, then you have a problem.
- Oct 21, 2006
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I thought I would share some of this information in reference to fuel injectors. Sorry some of the pages are upside down, so just rotate them.
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