I am surprised by the problems that have arisen with the ATI procharger. How many people have had engine problems after install? Major and minor? I know this has been eluded too in the past but I have not scene a discussion on the topic of a defect or flaw in the VQ35 as a potential problem with FI. I would not think that taking the engine to 350 rwhp would be a big mod, but. Not like NOS and TT to 800+ hp. Does anyone have any thoughts?

 

Does the engine need to have a new ECU and internals (low compression pistons, cams, etc.) to safely handle FI?

 

i dont know, but i am giong to let others with more money than me f*ck up their cars first ... i will wait patiently

 

There is no defect, it is called working the bugs out. And I am sure one or two more superchargers have been sold to people not on this forum. The car is new, the procharger used is relatively new model. There are variables like poor installs. I think the VQ is just fine. FI is not a minor mod and people act like 10.3:1 compression is not that high. You know what? It is too damn high for FI of any kind with some power and reliability. I am not going FI until I can get some 8.5:1 pistons and totally forged internals. I think it is dumb to put a supercharger on a car with over 10:1 compression and not understand when you blow it up. If you do just have some money allocated for a rebuild with the right parts.

 

You are right. What is the compression of our motors anyways? If you are going to run a blower you need the compression down to around 8-8.5:1, or you better be running race gas, or you can kiss your pistons goodbye.

As far as a defect in the motor. No way, these motors were not designed to be FI. The are highly tuned for NA. The higher the compression the the better for NA, the lower the compression the better for boost.

 

Running boost on a high compression engine such as the vq35 isn't necessarily bad. You just have to keep the boost low compared to what you could run with lower compression. This of course severely limits the power potential. In the case of the vq35, it seems that so far the rods are a weak point. So if you want big power, you'll have to go inside the motor and upgrade the rods along with some good low compression pistons.

 

Exactly. Limited power, weak reliability, expensive. Not a smart move unless you spend the money to build it right.

 

Just like the MKIV Supra there will be a learning curve with this motor. It will take some time but eventually we will know the limits of a well tuned stock motor with FI. And we will also know what exactly needs to be changed to make a lot of power, meaning 650-750rwhp+. It doesn't seem like many people want to take their 350Z to that level yet, and it's most likely because no one wants to pay the R&D to get there. But there are some people working on it


Ryan
350ZMotorsports.com

 

I think it's a conspiracy by Nissan. They purposefully used a weak rod so that 350Z can't be FI reliably and handle as much boost.

When they build a VQ33DETT or VQ35DETT, for GT-R or more powerful car, they would switch out the rods.

Bad nissan, bad!

 

No they can buy weaker rods cheaper and they do the NA job. They have to spring for more expensive forged rods when they FI a car from the factory because it is cheaper than all the warranty work they would obviously have to do if they used the cheaper rods.

 

the cheap rods are reaaaaaally cheap though, like $30 some bucks each. If they spent $200 for 6 rods, they could have a bullet proof engine.

 

I have been in this forum for a while, and I have read several times that the rods in the 350 are weak. Where this information did came from? Because, I haven’t heard of engines breaking their rods…
As for FI, I agree with Mr Potato Head, the compression in the engine is too damn high for ANY engine. The same problem happened when my brother installed the ProCharger in his LT1 Z28. Detonation is so much easier because of the high compression that if it goes lean…BOOM!!!
I’ll bet that the problems with all the 350Z’s that broke had to do with poor supply of fuel. It’s not the same to get a little detonation in FI with 9:1 than with 10:1
With the higher compression, detonation, even a little, is mortal…

 

I'm actually going to replace a lot of the internals since I'm going TT. I'm looking at the engine parts that SGP Racing carries. This will of course make me wait until next summer to have a TT Z but, I think it's worth it.

 

werd

 

I am in the same boat with toykilla I am wanting for everyone else to BETA Test these aftermarket products.

 

I agree my 1985 300ZX Turbo was 7:1 compression from the factory running 4psi of boost. I added a varible boost adjustable gauge and ran the boost at 15psi for 10 years without any problems. I still have the car (same engine with no rebuild and the same turbo charger still on the car), 287,000 miles. The lifters and valve springs finally gave out. Oh 15psi gave me 320rwhp.

 

Most of the information in the thread is not true.

The VQ is NOT a weak motor and it WAS built with FI in mind. They already have a VQ35DETT over in japan.

The basic fact is that you CAN run boost on higher compression motors, you just run less boost.

The key is in the TUNING.

If you do nothing else but lower the compression on a particular motor....yes you will be able run more boost but each pound of boost is LESS effective that on a higher compression motor. Thus overall the motor will make the same amount of power with lower compression and more boost as it did with higher compression and lower boost.

When you add boost to a motor you effectively raise the compression. For example (this may not be precisely mathmatically accurate but it's just an example) a standard VQ35DE 10.3:1 compression motor with say 7 pounds of boost will have a comp ratio after the boost of around 12:1. The same motor with compression lowered to around 8.5:1 will be able to run say 14-15 pounds of boost and reach about that same 12:1 compression ratio.

The thing is both motors will be running right around the same HP, but one has much more boost.

THE KEY AGAIN IS TUNING....I doubt anyone has blown up a VQ35DE with forced induction yet because of too much power since it took quite a few years with the maxima guys (VQ30DE 10:1 comp) to find out that with proper fuel delivery you could take a stock VQ up to 18lbs before it would "pop". 7 lbs is NOTHING as far as FI goes for a 10.3:1 motor.

 

So what's the consensus here? Should I replace the pistons (from stock to 8.5:1), replace the rods & retainer? Or am I just wasting money by changing those internals and should just go ahead and install the TT? So, from what people are posting here (and take into consideration that I'm fairly inexprerienced mechanicaly speaking), if I were to install the TT on a completely stock Z with the stock compression I should dyno more RWHP than a stock Z running at 8.5:1 compression (both scenarios would be running the same amount of boost)? If so, then I guess longer engine life would be the only benefit of the lower compression right?

 

Now im probably way off on this, and dont really know how to say it, but here goes...

I think running a lower compression with higher boost numbers gives you a larger volume of air. More air + more gas = more boom right? So if you run an engine with 10:1 compression at 7 lbs of boost to get an effective 12:1 compression, you will have a smaller volume of air. When compaired to a 8.5:1 at 14 lbs of boost.

Again, this is just something that kinda makes sence to me. In the end it does come down to tuning. Makes me miss my carb. days. You just get a bigger carb. and you get more power.

 

Hey you can run your motor on the ragged edge or you can do it the right way. There is NO car that comes FI with high compression. There is a reason for that. We are not talking about what CAN be done. We are talking about reliably adding power through FI. Why don't you let us know what the compression ratio is on that TT VQ35 over in Japan?