tuning help

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tuning help

Postby v8coupe » Thu Oct 02, 2014 5:02 pm

I recently upgraded my turbo to an Hx35W with a 12cm housing. I'm running the truck non intercooled and non wastegated as it was before. My Truck is a 91 non IC truck. I also installed an M&H M2 fuel pin. I've dialed the pump in as much as I could while on the road. EGT's stay under 1000F most of the time, only briefly breaking into the 11-1200 range while going up large grades with my loaded trailer. I seem to have a dead spot down low especially when empty.


My steady state cruising EGT's are in the 700-800F range. Any suggestions as to what to adjust next or is it bigger injector time?

TIA
Sean
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Re: tuning help

Postby Dan NJ » Thu Oct 02, 2014 5:42 pm

May have too much pre boost? Is it belching a ton of smoke when you are in the " dead spot"?
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Re: tuning help

Postby v8coupe » Thu Oct 02, 2014 6:18 pm

No Not much at all very light puff when I get on it. egt's don't really get rolling until boost starts coming on. I don't have a tach, but I can see the boost start to come on then it jumps from 10psi to 20psi and climbs to 28-30psi.
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Re: tuning help

Postby fatty » Thu Oct 02, 2014 6:43 pm

How high up is the starwheel? You may have it up too high for the amount of fuel your pump can push. Try turning it down a little.
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Re: tuning help

Postby v8coupe » Thu Oct 02, 2014 7:42 pm

fatty wrote:How high up is the starwheel? You may have it up too high for the amount of fuel your pump can push. Try turning it down a little.


I've lowered it ~1.5 turns since I put the pin in. It has helped, but the dead spot seems to be there. Should I add another turn to the pre boost?
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Re: tuning help

Postby Remps » Thu Oct 02, 2014 8:16 pm

It is mostly the curve that the m2 pin has causing the dead spot. It is shaped to not bring in much fuel till the pin is about 1/4 of the way down, then you get a bunch of fuel. You can try and tune around it and train your right foot to be ready for once it travels past the dead zone. Or sell it and buy something like a BD pin. Or take a dremel to it and flatten the curve out a little at a time till you like it. Or crank the smoke screw right down and give the pin a head start.
'90 D250 R/C,727,IC,6x.009's,1/8" bump,fuel psi,straight pipe w/5" stack.
'90 W250 R/C,47rh,K@N,HX35,1/8" bump,2nd gen IC,boost,egt,trans temp.3.07's.
'96 2500 S/C L/B,2wd,NV5600,3.54 L/S,cai,egt,pacbrake,mbrp exhaust,10 plate.
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Re: tuning help

Postby cougar » Sun Oct 05, 2014 9:50 am

Remps wrote:It is mostly the curve that the m2 pin has causing the dead spot. It is shaped to not bring in much fuel till the pin is about 1/4 of the way down, then you get a bunch of fuel. You can try and tune around it and train your right foot to be ready for once it travels past the dead zone. Or sell it and buy something like a BD pin. Or take a dremel to it and flatten the curve out a little at a time till you like it. Or crank the smoke screw right down and give the pin a head start.

This is pretty much what I encountered with my old 91. Between ditching the M2 and going back to the stock pin and fine tuning the smoke screw, I got just about all lag out and got rid of my haze.
RIP 91.5 W250 5 speed. The great experiment.
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Re: tuning help

Postby RCCUMMINS89 » Sun Oct 05, 2014 12:22 pm

A progressive ramp, which is found on virtually all aftermarket fuel pins, is less than ideal for most situations. A linear ramp, such as found on the stock pin and the BD pin, I have found to be a lot more smooth throughout the transition.

There could be other factors playing into the dead spot, such as timing, or tuning... but, swapping in a stock pin just to verify might be worth it. If it is to be the case, modify the m2 pin, or go with a BD pin.
89 RC on shortened 92 diesel frame - NV4500 w/dual disc/4.10s on 37s. - Self built pump, "hot screw", lots of timing, True high volume low pressure lift pump, 62fmw/68/.7gated, 77lpm SAC Inj., Studs/O-rings,- 423/1220 Mustang - 11/16/2013 http://www.TheHungryDiesel.com full line dealer, if you don't see it please ask.
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Re: tuning help

Postby v8coupe » Sun Oct 05, 2014 8:15 pm

RCCUMMINS89 wrote:A progressive ramp, which is found on virtually all aftermarket fuel pins, is less than ideal for most situations. A linear ramp, such as found on the stock pin and the BD pin, I have found to be a lot more smooth throughout the transition.

There could be other factors playing into the dead spot, such as timing, or tuning... but, swapping in a stock pin just to verify might be worth it. If it is to be the case, modify the m2 pin, or go with a BD pin.


I had a stock pin in before the M2. I drove both loaded and unloaded on the stock pin and M2. the M2 is much more responsive once the engine gets moving. I bought the less aggressive pin knowing I'm going manual. is this a factor of the Auto and 3.07s being slow to get moving?

I have not touched the fuel power screw at all.
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Re: tuning help

Postby RCCUMMINS89 » Sun Oct 05, 2014 10:02 pm

It very well could be the fact that the power screw has not been touched. Also could be the converter.
89 RC on shortened 92 diesel frame - NV4500 w/dual disc/4.10s on 37s. - Self built pump, "hot screw", lots of timing, True high volume low pressure lift pump, 62fmw/68/.7gated, 77lpm SAC Inj., Studs/O-rings,- 423/1220 Mustang - 11/16/2013 http://www.TheHungryDiesel.com full line dealer, if you don't see it please ask.
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Re: tuning help

Postby jay » Wed Oct 08, 2014 9:52 pm

Have you bump timing up?? I would turn up the power screw to a safe level and bump timing up to about 6 degrees makes a big difference
92 D350 CC bd diesel fuel pin and governor spring timing advanced 6 degrees power screw turned.Had a 93 D250 CC denny t fuel pin 3200 governor spring timing advanced 6 degrees power screw done 100 hp DSS injectors he 351 turbo dual disc clutch
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