Engine/Transmission (1998.5 - 2002) Gas v/s Diesel concepts

[RobertMiller1]

It appears considerations of fuel-boost relationship is very different between turbo charged diesels engines and gas engines.



In a gas engine like my twin turbo Supra, If you added boost, you better be sure you had a fuel map rich enough or bigger injectors to support the additional boost or you could lean out, exhaust gas temps would sky rocket and you could detonate destroying pistons.



It apprears that diesels are a very different animal. Instead of more fuel enriching the charge and cooling things down, to avoid a lean/ detonation issue as is the case in gasoline turbocharged engines, the extra fuel injected into the diesel will increase chamber heat-ignition... .



Adding air or increasing boost actually cools down the charge (to a point i gather) and exhaust temps decline. exact opposite of gas turbo engines.



The reason I am seeking to understand this is I was considering 275 injectors, but SuperChips recommended against it. Purely defensive medicine I am sure, as the richer injection could raise Exhaust gas temps, without other compensating factors like better exhaust flow, cooler better induction and/or more boost.



Am I understanding this correctly?

 

[ToolManTimTaylor]

Originally posted by RobertMiller1





In a gas engine like my twin turbo Supra,

Note to self "never talk to this man again #ad
TT MK4 2JZGTE

 

[snowracer69]

Originally posted by ToolManTimTaylor

Note to self "never talk to this man again #ad
TT MK4 2JZGTE

What he said!



But yes, you basically have the idea right, except 275's will be perfectly ok with other stock gear like your stock turbo and exhaust.



So, on to more important things... . what's the supra run in the 1/4, and when can I drive it?



Supra = nicest ricer on the road! (note: I don't honestly consider the supra "rice", however it's built in the same country as most rice, therefore it gets the namesake)

 

[RobertMiller1]

2JZGTE

One awesome car. $1200 in parts (BPU) and you had 400 rwhp.



My gtech said 0-60 4. 3 sec.

I could never hook up at Ennis.



I always wanted a world class sports car, and that was the finest... . Till I got caught in a golf ball hail storm racing home trying to keep in front of it ONE BLOCK FROM HOME.



Beat that aluminum hood and top to hell. Broke my heart.



Some mother bought it for her 18 year old son. I tried to talk her out of it. Even gave him a ride in it that scared hell out of him. "... oh, I'll never drive it like this... " Yeah right...

 

[RobertMiller1]

1/4 mile

A bpu supra runs 12. 5 sec quarters.



bpu: turbo back 3" exhaust no cat.

fuel cut defensor

increase boost from 11lb to 19 ft lb with boost controller



NGK race plugs (all that would work)



I never did better than 13. 5 @108 because I simply could not lauch over 2800 rpm. If I got into the power, it would go sideways. My posi clutches in back were just too worn.



When I found myself going sideways, and coming to a stop facing backward in the OTHER LANE I quit drag racing.

 

[justinp20012500]

RV 275's

The 275 are a perfect fit for your appilcation... The only thing you would have to worry about would be frying the converter if you have a heavy right foot.

 

[RobertMiller1]

no converter

No cat on this truck. Guess California 2001s had them eh? looks like muffler and resonator only.



Superchips reprograms the computer, advances the timing etc. They recommended against the injectors. 275s are fine on a stock truck, but I need to look at exhaust temps first.



robt

 

[Forrest Nearing]

the biggest difference is that in a gas engine, the fuel is drawn in and compressed with the air, so you have to worry about the mixture pre-igniting from the heat from the compression... boost just increases compression, which increases heat...



with a diesel, the air is compressed and THEN the fuel is injected and ignited BY the heat generated...



so basicly the bottom line is that diesel is the **** and gas sucks.



Forrest

 

[ToolManTimTaylor]

Re: no converter

Originally posted by RobertMiller1

No cat on this truck.

He means Torque Converter.

 

[JBlock]

275RV and Superchips OK

Hi



I am running this same combination, with the Superchip Power Programer on 50HP performance towing, no problems, It not as fast as the comp on 1x2, but it is a lot simplier with no cluter under the dash. Makes 27 pounds boost with a TAG in the inline.



I did not know superchip power programers advance timing, are you sure?



JB

 

[RobertMiller1]

Super chips

no not sure.



I called SuperChips. First he said it was proprietary info and he couldn't share the info. I then said hold on a minute. I just paid $350, and I dang sure had a right to know how he modified my engine. He got off his high horse a little bit. I then asked questions like " does it advance timeing? increase boost? increas fuel mapping things like that and he said "yes"...



but I was pretty sure it was a buzz off answer.



I am happy with the performance, but I don't like being blind. don't like their attitude.

 

[RobertMiller1]

not entirely acurate

forest,



That may be correct in some cases, but my supra was common rail direct injection.



What you described I can see for a gas engine using throttle body injection.

With diesel you don't have the preignition problems.



In a diesel the quicker you can begin the burn process the more benificial. Higher Cetane fuel helps in that area Not so with gas. Higher Octane helps delay the ignition process and can support higher compression ratios and advanced timing.

 

[Forrest Nearing]

Re: not entirely acurate

Originally posted by RobertMiller1

forest,



That may be correct in some cases, but my supra was common rail direct injection.



What you described I can see for a gas engine using throttle body injection.

With diesel you don't have the preignition problems.

it's correct in all cases... the air/fuel mixture is compressed together in a gasoline engine... the fuel injectors spray fuel at the back of the intake valve and the air and fuel are drawn in together and compressed...



with a diesel the air is drawn in and compressed and then the diesel is injected at super high pressure directly into the combustion chamber with both valves closed as the piston nears TDC. no fuel is drawn into the cylinder past the intake valve, and the air/fuel mix is not compressed, just the air.



Forrest

 

[RobertMiller1]

thanks

thanks Forest, learned something.

 

[Forrest Nearing]

no sweat, it took me a little while to wrap my brain around it after being around gas power for so long... diesels really are amazing little machines... I love 'em. wish everything I owned was diesel powered



Forrest