What do i need todo

[Guest Anonymous]

I finnaly got my hands on a L28T. and i'm looking to build it up, with a goal of an 11 sec 1/4 mile, i know this is going to be time and money, but what do i really need to have/do to reach this goal. Do i really need to spent the money on expencive internals. eg, forged pistons, and such. or does running stock internals sactifise relibility. please post your thoughts..

 

Thanks

-Gonzo-

-70 240Z (turbo project)

-72 240Z

[Z-Gad]

I know Scottie GNZ can vouch for this...there's a blue 70 240z here in Orlando that ran 11.7 @ 119 on street tires and pump gas.

The engine was stock internals, but ran an SDS, T3/T4 turbo, bigger injectors, huge intercooler, with bookoo boost, 3" exhaust, etc and a very experienced driver. I would have to say that you don't HAVE to beef up the internals to run 11's, and stick you $ elsewhere...like...the best intercooler you could afford, better engine management, large exhaust, etc

[Guest Zcarsmakemyheadhurt]

Fuel system is key bigger injectors and a stand alone fuel computer will let you get the best of any turbo you install.

[Scottie-GNZ]

This question always seems to turn into a big debate. I will throw in my $.02, and rest assured that it is mostly from experience, but I do have my biases .

 

Just saying you want to run 11s begs for more questions. Low-11s or Hi-11s? When you get down to this level, that is a big HP difference. Pump gas or race gas? Street tires or DRs/slicks? If your goal is to run low-11s on pump gas with street tires, you better do the internals because you will need lots of HP on the top-end to make up for a slow launch and with pump gas you are putting your self on the edge.

 

Regardless, the primary focus should be on components that eliminate detonation. I could have said components that make more HP, but I prefer the approach of eliminating detonation. The more effective you are at limiting detonation, the more boost you can run, the more HP you will make. Forged pistons are better at tolerating detonation, but your primary focus should be to eliminate detonation. I am not saying you do not need forged pistons, but if the goal is hi-11s at the track with sticky tires and NOT PUMP GAS, IMO you do not need them. What this means is no cheap, OEM I/Cs, no fiddling with the AFM and stock ECM, no stock injs/turbo/pump, etc AND NO STREET TIRES.

 

I know folks will make claims with OEM I/Cs, but there is no way I can be convinced that you can double the HP of a L28ET using an I/C that was designed for an engine that makes less HP than a stock L28ET. Folks pushing Starion, Volvo, etc I/Cs to the limit might be surprised at the pressure drop and intake temps. The only exception to this would be the med & big NPRs, other big turbo-diesels, 944T and MKIV SupraTT. Whatever you do, do not skimp here. Because we measure boost at the intake, it is difficult to tell when the I/C has hit its flow limit. What we end up doing is turning up the boost with little increase at the intake but a now with a lot more heat. Most aftermarket I/Cs have a flow rating. Divide that number by 1.5 to get an estimate of how much HP it can support before encountering pressure drop.

 

The stock injs, pump and FPR have to be upgraded. For a rough estimate, use a formula that estimates the HP an inj can support at 80% duty cycle. It is a conservative estimate and running a higher DC and more fuel pressure will net more HP but it is a good baseline.

HP at 80% DC = (inj flow rate/7) * # of cyls.

E.g., the SVO 370cc injs would equate to about 320hp and with a higher DC and fuel pressure, a lot more. You need an adjustable FPR to be able to change the FP and you must have a pump that can match that fuel demand.

 

I am not going to get into a debate on the benefits of a programmable system or which one is best, but I would not run this HP level w/o one. W/o one, you can certainly fool the system into dumping more fuel but you are typically stuck with that extra fuel in all driving conditions. But, you need more than added fuel at WOT/high boost, you also need timing or to be specific, be able to retard timing as boost increases. Add-on systems like the MSD work but you end up nickel/dimeing yourself and spending almost as much as a programmable system in the long run.

 

Now that you have the components that can eliminate detonation, you can now turn up the boost. The stock turbo pushed to 17-18psi will net lots of HP but with a lot of heat and on the ragged edge. The right upgrade, like a t3/t04 hybrid will make lots more HP. Along with the turbo is the exhaust flow and a restrictive DP and exhaust will only serve to put backpressure in the turbo generating more heat. The best DP available and a 3" free-flow exhaust is the way to go. Note how many times I mentioned the word HEAT. It is the enemy of turbo systems.

 

Tires, my favorite hot-button. Unless you have lots of seat time, trick suspension and running on a well-prepped track, it is hard to run 11s on street tires. It takes more than just big HP to run quick ETs. The 60' is real key. You lose/gain .15 in the ET for every .1 in the 60'. If you have to buy tires anyway, get a pair of Nitto DRs for the rear. They will gain you, on the average, .3-.4 in the 60' and that equates to about .5 or more in the ET. Folks end up spending $$$ to gain .5 on the ET when that is there to be gained by improving the 60'.

 

In summary, the car Z-GAD referred to has the following: 71 240Z, 3.70 LSD, 225/50-15 street tires, stock L28ET longblock, re-ringed, fresh bearings, Spearco I/C, t3/t04 turbo, SDS, 600cc injs, Pierburg pump. The time was accomplished by a driver with lots of seat time and it was run with 22psi boost. Do I recommend this? NO! The owner also followed the philosophy to run it hard and if it breaks just get another JY motor. As you can see, the focus was on the components I mentioned. That time eqautes to about 350RWHP. If you plan to push the engine beyond that and insist on running pump gas, you need to do some internal work.

 

Having said all of that, if you have the $$$ for forged pistons and want to do them, by all means. I just think folks underestimate the quality and strength of the Nissan components.

[Guest Anonymous]

WoW Scotty, thanks for your time and info, and thanks to everyone else.