Hi

I was wondering how many maximas had built engines ... I mean built for performance with aftermarket pistons etc.

I am seriously considering building my own engine for my Turbo so I can turn up the boost . What are the limiting factors for turning up boost? I have heard of Sentra engines running 15 psi without any problems ... even the unbuilt ones ...and not DET versions. Are they at lower compression? Just wondering? I know ours is at 10:1 (if I remember correctly).

One key thing is not to detonate .. so as long as I don't detonate, I should be OK? Just wondering what other people's experiences were.

I have read of people speculating about good configurations. The only person I really know of with a built engine is Turbomax.

Thanks

Nigel

 

Don
Mardi
Phil

 

Matthel does.

Personally, and not knowing a whole lot about the limits of our engine, I would go to about 12-14 psi maximum on our internals.

 

You should talk to Yo_Its_Ok aka Hogan. He's got experience with blown Nissan VQs.

Stereodude

 

At this time, my motor is in the machine shop getting 9:1 compression pistons, rings, and stronger valve springs along with the rest of the machining. I bought these from JWT and they're from the VQ30DET motor sold in the Japanese domestic market.
Remember, when you high boost your motors without lowering the compression and with no aftercoolers, you're building a time bomb not a reliable motor for your every day ride
!!

 

What is the stock comression?

SuDZ

 

10:1 or 10.5:1, but i think its 10:1

 

10:1

 

It's 10.5:1 per my Nissan FSM.

 

I am seriously considering building my own engine for my Turbo so I can turn up the boost . What are the limiting factors for turning up boost?

**Limiting factors or turning up boost:
*Detonation from too much boost or not enough air and fuel.
Solution- Bigger fuel injectors with ECU calibrated to use the bigger injectors to handle your increase in power. Not sure that we have come to that point yet, but I am sure that some people are rapidly approaching the point where replacing their injectors is necessary.
Solution- Bigger throttle body and mass airflow meter. More air is a good thing, but I am not sure that we have maxed out the ability of our stock throttle body and Mass Airflow Meter. Maybe tweeking the MAF meter to open up more (closer to 100% open at WOT) would be helpful, but then again I think that this has been done with so-so results. Might as well get your intake manifold ported, polished, and Extrude Honed and port and polish your heads to maximize the amount of airflow you can get into your engine. That and port match the heads to the intake manifold so there is a smooth tranition between the two. Might also want to check into getting the Middle East Variable Inake Manifold for our cars as well.
Solution- Lower compression pistons will allow you to run more boost safely. Lets you run more on boost than on your engine (your engine drops in the amount of power that it alone makes and allows you to pump more power out of your turbocharger/supercharger setup.
Solution- Find a way to get the temperature of the air that is coming into the engine cooler while it is coming from your source of forced induction. Typically this involves one or all of the following: A front mounted Intercooler, an aftercooler mounted in the engine bay, or using a water injection or nitrous injection kit. You can use the N2O injection kit on the fins of the intercooler to cool the incoming air and then send it through an aftercooler and/or through a water injection mist. All of these things significantly lessen the temperature of the air that is coming into your engine and will allow you to run a higher boost level to a point. After a while it would be better to get your engine built because you just want to go boost crazy and you will be exceeding the amoung of boost that your intercooling/aftercooling/injection methods can support. These methods will also lessen the amount of boost you get but that is a good thing. The reason is that you will be getting better boost with more oxygen crammed in it. Think of it like this- Would you rather be breathing in air that is at 200 degrees or 75 degrees? So would your car. If you lose some boost in the process it is all for the better that you get more densely packed oxygen with a lower boost number rather than high boost numbers and a low density of oxygen.

* Tranny is a weak link.
Solution- Upgrade your tranny internals (lightened flywheel and Heavy Duty clutch for 5-speeds) (Level10 built AT or LSD tranny upgrade soon to be out from Shadow). Add a transmission cooler and an engine oil cooler since the engine oil will be going through the turbos (don't want to coke them by too much heat).

* Engine blows out the spark
Solution- Doesn't seem to be a problem with our cars and their Direct Ignition systems. I think that proper tuning such as proper spark plug selection and plug gapping for higher boost levels are in order. Seems like our cars can handle what we throw at them with their stock ignition systems.

*Extra horsepower isn't utilized properly (too much wheelspin)
Solution- Front radial arms, Stage II Subframe connectors, FSTB, RSB, polyurethane front end link bushings and maybe even the RSTB. Could go with some polyurethane motor mounts and transmission mounts but time will tell. A good set of shocks/springs is in order. Full Drag Spring package if racing is mainly what you want to do, or a good combination of aftermarket springs and shocks if you want it to handle also.

I have heard of Sentra engines running 15 psi without any problems ... even the unbuilt ones ...and not DET versions. Are they at lower compression?

**Could be. Might be using N20 to cool down the incoming air or using an intercooler.


One key thing is not to detonate .. so as long as I don't detonate, I should be OK? Just wondering what other people's experiences were.

**Detonation is not a friend of boosted cars young grasshopper.

How do I know about all of this? SC'ed 89 Saleen Mustang

 

Maybe you should check out the Variable Intake thread.

 

Justin. I think most of the stuff for the VQ is covered except for a good/relatively inexpensive way to control ignition timing. Right now standalones are the only way. I wish someone like Hondadata would come out with a programmable ecu that still uses the oem ecu for idle/accessories/cold start ect...

 

I was hoping to work on one from the yard, but I haven't had the money. I know a bunch of people who have a lot of experience building motors....

 

Sorta. Seems the dealership fed her a line of BS or something. I grilled them on the phone and gave me the, "We can't do this, We're not allowed to do that." BS and all that jazz. She talked to them and they swore up and down to her that they did all the stuff they told me they couldn't do. I asked her about that and she just said I must have talked to someone who didn't know what they were talking about.

So now I'm driving around a car that still needs an alignment. I'm going to take it someplace else and have them do a full inspection on it (but I'm not going to have them fix anything). Then I can bash the dealership over the head with the findings of the other shop when they find nothing wrong. Right now I'm ****ed off at Nissan. I'm probably going to sell the car and buy a Lancer EVO VII in the fall.

Stereodude

 

The warranty is transfered now. It took about a week to transfer. It's pretty sad when I want to go a step lower on the rung of dealerships. Apparently only Mitsubishi dealerships are worse than Nissan dealerships. However, the EVO VII is fast enough to make me forget about that detail.

Stereodude