TurboTim

iTrader: (9)

we all need to get bigger turbos.

Maybe all the rods look like this, giving a nice low compression?

Leafy

iTrader: (1)

Come on tim, you know that rod length does effect compression.

concealer404

iTrader: (3)

Doesn't matter, still made more power than my limpdick BP.

Also: I'm pretty sure my current seat pressure is like..... 110lbs. NECESSARY.

TurboTim

iTrader: (9)

I will say it does. A bent rod (or shorter rod length) affects clearance volume, no? You have more combustion chamber volume with that bent rod.

Come on, all the cool kids run bent rods. You really think Lars wanted those rods for a damn lamp post?!

Displacement stays the same.

karlou426hemi

Little update on the car...

First it is still alive with still perfect compression across all cylinders

went to the strip last friday and did around 6-7 passes and managed to do a best of 12,70 @ 111.1mph witch I consider pretty decent considering we had totally worn out tires that are probably more than 5 years old and a totally full tank of gas....

I also realized how the 6 speed is geared like crap for a quarter mile lol. It is as bad as it is fun like hell on the street.... first gear is so short and shifting 5 gears in a quarter mile is a little too much shifting for my taste.

18psi

iTrader: (76)

sounds like you need to get in on the 3.3 fd group buy

Twodoor

iTrader: (2)

Naaa, run a 4.3 and start off in 2nd gear

For myself eventually I want a 3.63 with a 6 speed. The 3.3 seems a little extreme for now. If I build the engine and start making huge power perhaps i will think differently.

Keith

karlou426hemi

can't go 4.3 id had to shift 6th at the end of the run.

My father is thinking about ms3x rods and valve springs for next year so ill probably just bump the limiter to 8.5k so he'll stay in 4th up to roughly 115mph...

locomonkeyboricua

Based on 1/4 mile times I would say 300hp is about right. Great job. Love to see more videos. If you could do a 0-100 pull that shows your rpms that would be awsome. Im working on a budget turbo build and have a 6 speed and a gt2876r I may use. im Always afraid of going over 250wtq due to stock rods your dyno shows you right at it and 300whp so I hope your motor last a long time.

Twodoor

iTrader: (2)

With standard diameter tires and a 4.3 in a 6 speed 7000 RPM in 5th is 111 mph... starting in 2nd and running to the top of 5th you would be doing one less gear change than you are now. I know that at the drag strip "terminal speed" and "trap speed" are two different things. Since trap speed is the average over the last 60' of the track, your actual terminal speed will be higher... but you can run 5th out to 7400 RPM and still be in 5th at the end of the 1/4 with the 4.3.

Keith

flounder

What size injectors and fuel system? stock pump? returnless?

karlou426hemi

stock fuel system exept 550cc injectors,

Can't go any higher than stock limiter because i am still on the stock ecu so ill live with the gearing i have now.

locomonkeyboricua

What brand 550 injectors? I hope to see more people get away with stock 300hp engines and like to see them last for years. Cool to see the old turbo working great.

Twodoor

iTrader: (2)

I am hopping to manage this with the EBC function of the megasquirt. I plan to limit torque output to 225 lb-ft throughout the rev range, by running low boost (10 to 12 psi) in the lower RPM range, and ramping it up to higher boost pressures in the upper RPM ranges I hope to maintain that 225 lb-ft all the way through to redline. 225 lb-ft at 7000 RPM = 299.89 Rounds up to 300

My only concern is I may run out of injector running E85 and the RX8 injectors at that power level. If I start getting ridiculous duty cycles I will need to back off until I get new injectors. I can't wait! My turbo system is almost finished, COP has been shipped, my repaired MS3 has been shipped, clutch and flywheel are ready to go in, and Xida clubsports should ship this month!

Keith

locomonkeyboricua

Good idea. I was thinking of managing tq by ignition timing map. Around 3-4.5 k keep timing down to lower the tq output and then tune it from 4.5 -7.5 for max power. So after I shift I should stay in the upper power band. The boost method works great as well.

locomonkeyboricua

Does anyone else in here think that the 6speed helps keep stock engines with over 250whp running due to the shorter gearing keeping the rpms up there for putting less stress on rods??? Just a thought.

Twodoor

iTrader: (2)

I don't think so, I will check on my excel spread sheet of Miata gear ratio's when I get home. Using that I can easily see what RPM you drop to when shifting at 7000 RPM in each gear on both transmissions. I am at work right now so I can't access it.

Keith

Twodoor

iTrader: (2)

Allright, here is the data.

Gear change . . . . . . . . .5 speed. . . . . . . . . . . . . . . . . .6 speed
1 to 2 . . . . . . . . . . drops to 4100 RPM . . . . . . . . . drops to 4200 RPM
2 to 3 . . . . . . . . . . drops to 4800 RPM . . . . . . . . . drops to 5100 RPM
3 to 4 . . . . . . . . . . drops to 5300 RPM . . . . . . . . . drops to 5350 RPM
4 to 5 . . . . . . . . . . drops to 5700 RPM . . . . . . . . . drops to 5550 RPM
5 to 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . drops to 5900 RPM

So, the only significant difference is on the 2 to 3 shift the 5 speed drops 300 RPM more than the 6 speed. Not enough of a difference to make the pistons or rods last longer at higher torque values.

Keith

locomonkeyboricua

Well so much for that thinking. I swear when I was watching youtube of the 6speed with I think 4.10 it would not drop much seem to always be above 5k. But maybe I was wrong. Why do people say the 6 speed gearing is so short if only 300 rpm or so shorter.

Twodoor

iTrader: (2)

I didn't put the mph in the chart... Short gearing has to do with what speed you gain between shift, not what RPM you drop to after the shift.

Keith