PhatManBUD

What RPM do you guys normally shift at when racing with a single turbo? stock redline is 8k.

What if you have single and a street ported motor? Can you push the redline more safely?

I know at certain rpms you can feel when the power drops off and you should shift, but im just wondering if you have a big enough turbo that wouldnt run out of breath, whats the max rpm you can shift at.

MARTIN

well I dont know the recommendations for something like pushing the rpms, but I usually shift at 8k. I have a stock port motor and it pulls hard hard till I shift. I just never wanted to take it more than that. Theres no need to . I have a microtech by the way.

Railgun

All depends on what your powerband looks like. Dyno it to find out and go from there.

1QWIK7

iTrader: (33)

exactly

no need to rev any higher when you're not making any more power/actually dropping power when you dont have to..plus if you're trying to get the best ET, you would lose time..

hotrodrx7

Ideally, you shift so that you maximize the area under the HP curve between the RPM where you shift and the RPM that you pick up in the next higher gear. This is past the point of maximum HP on the curve.

MARTIN

Whoever said shift at your peak Hp, is dead wrong. If you take a lil longer to shift, it might(depending on your gear box) land you in perfect spot on the powerband on the next gear.

smg944

iTrader: (34)

i shift first gear at about 8200 because its breaking loose. after that, around 7400 rpms. that gets me my best e.t. of 12.5 at 116mph, with a 2.19 60 ft. btw i agree with getting a dyno sheet to find out your best shift point, helped me out some.

Nihilanthic

Generally if you get experienced and you get a 'feel' for when to shift, is when you should. That is, when you feel the torque begin to drop in taht gear so you shift up into the next one. On some cars its VERY exaggerated, like say a TPI Camaro. Good lord!

Now, with cars that have torque build as rpms increase, or hold steady, just go to redline. Learn to shift by ear.

ismaelruiz

Bridge ported or peripheral port rotary engines shift at 11000rpm or more. I shift at 9000rpm in my street ported turbo car. At 9000rpm the horsepower curve on my engine is still going up but I don't want to push it too hard.

fastcarfreak

I shift just after 7k usually with my car. Power usually peaks at about 6800 and drops off a bit anyways.

Carl Byck

Keep in mind all these "higher" RPM numbers above assume proper balancing, and clearancing. The statement about shifting at higher RPMs with a BP, or PP, is talking about where, when properly built, those cars make their best power, presumably such a motor is built right, but if it's your motor, you want to ask the builder what your safe max RPMs are for the particular build.

PhatManBUD

So is the stock redline 8,000 actually and not 7,500. Is those lines is just where it starts to warn you you are approaching redline. I know every car depending on their setup is different depending on where their power band drops off. But i just wanted to know if youve got single and a street port, where does your powerband usually drop off, and if its safe to go all the way up there to get max use out of that gear if you really needed too.

cause i know iwth my brothers mr2 turbo. the thing runs out of breath like 500 rpm before hititng redline and so he shifts before.

Wargasm

The only way to really figure out when to shift is to dyno your car first. Then use Excel to make a spreadsheet showing the power at the wheels after taking into acount the gear ratios. Shift when one of two things happens: 1) you hit your redline for your engine (taking into account any mods that might raise or lower it).... 2) Your force at the wheels in the next gear will actually be higher than your current gear.

I can tell you that for most FDs, you want to shift at 8000 in every gear. This is because your next gear will drop your force to the wheels, but you can't keep holding it because you've hit the stock redline...

If you have mods to support high RPM operation, you may even want to hold out until around 8500 or so, especially in 1st and 2nd.

I can tell you that I've dynoed my single turbo many times, and the only place where I don't shift at 8000 is from 4th to 5th. Because I've installed a shorter-than-stock 5th gear, I actually have more power if I shift from 4->5 at about 7500 RPM.

Unless you have some pretty good high-rpm mods, AND you have the fuel system built to support it, AND your ECU is mapped up to say... 9000 RPM... you should just shift at 8k.

To make it short, Single + Street Port does not do anything to move your safe redline up. If anything, the huge airflow will put more demand on your fuel injectors which I bet run at 90% or more even at "only" 7500-8000 RPM.

Nihilanthic

Generally where it feels the fastest, unless you have telemetry to coutradict it, is the best place to run your engine. When you feel it start to bog and lose torque, shift!

Engines that have all their torque up high like a race-cammed piston engine or a ported and/or big turbo'd rotary require you to keep it high. But, say, a torqier motor like most v8s or the 350Z's engine (or hell I think the SRT-4 tends to drop off at high roms) you feel it a lot more profoundly.

The worst exaggeration of this is the L98 motors in 3rd generation camaros/firebirds. Off idle it could pull stumps out of the ground and break your tires like a pro, but at 4,500 rpms the torque just took a nosedive. Power was the same from 4000 rpms to.. redline. It felt like it was just wheezing at 5.5K... you REALLY felt it! Fortunately, GM made the LT1s intake handle 8K rpms if your cam and heads (and internals) could handle it and were matched for it, so its not nearly as much of a truck/RV like engine.

PhatManBUD

8,000 sounds safe to me. i always thot it was 7500! i guess that was a good thing tho cause i never took it to 8. haha.

but so if i had single turbo and streetport, with the right fuel, 550 + 1300cc, and walbro pump, and powerfc tuned, would it be safe to take it to anything more than 8 (assuming i still feel power all the way up to 8 and possibly beyond), when racing, in the lower gears like you say?

Right now on this small turbo and intercooler my goal is 360 rwhp. Do you guys think this is possible with these supporting mods?

Street Ported Motor
Apexi Power FC ecu
HKS 50mm External Wastegate
HKS SSQ BOV,
3" Downpipe,
3" Midpipe,
Trust N1 catback,
Koyo Radiator,
Silicon Vaccum hoses,
SR motorsport 9.5 lb flywheel,
Clutchnet 6-puck clutch
Pulleys
Magnecor Spark plug wires
1300cc Injectors
Walbro 255 Fuel Pump
Sard Fuel Pressure Regulator
Removed A/c
Removed Smog Pump

I also plan on getting an Ignition amplifier, AVC-R boost Controller, and Engine Torque Brace. Ill just get it tuned for 14 psi and see what it hits!

Would this be enough to beat a stock svt cobra?





my ultimate goal is 420 rwhp tho. Need bigger turbo and intercooler! and 850cc injectors in the primary?