If you remember my review of my 420Ztt built by GTM, there have been a couple small issues that needed to be addressed. As mine was the first one done for a customer, and also done at the same time as their shop car, there were a lot of unknowns we had to see and address.

Well, I took my car back to GTM 2 weeks ago, and talked to Sam about all the little issues that were happening, including 1) hard starts idle fluctuating, 2) heat issues with the water temperature, 3) felt like power was dying up top a little bit, and 4) upping the boost a bit.

Sam called me at the end of last week, letting me know that with the 5" deep core intercooler with the APS Extreme kit, the radiator is just not getting enough air, and the stock fans aren't pulling hard enough. He pulled a few strings, and within 2 days, he had some new fans on hand, pulling more than double the cfm compared to the oem ones. He then talked to me about boost. He asked me if I wanted to break records, or to have a completely reliable daily driver. I wanted to go big originally, but what he said made sense. I spent all this money on the car, because i want to drive it daily, everywhere I go. Without having to worry about anything. I don't want a dyno queen. I want a beastful daily driver. I'll let his shop car do the R&D to break records.

So we went on with it. I called him last night to see if everything would be on schedule for pick up today, and he said yes. So i headed over this morning to pick her up. Sam finished up with the car late late last night, and spent the whole night double checking everything to make sure it's running PERFECTLY. Called me early in the morning to pick up, but I was still sleeping. I stayed up in his shop to double check every little detail for my car until I picked up this morning at 11am. THAT, is service. A little overboard even. But much much appreciated.

So with all the issues addressed, he gave me 3 maps to choose from. One is the low low boost at wastegate pressure, about 600+rwhp/600+rwtq, to be run on 91 octane only. Second map, slightly more aggressive with 1 more psi of boost, to be used with 91 octane + water/methenol injection. Third map, most aggressive, to be used with race gas and methenol, set at 18psi. These are all aggressive in relation to eachother, but VERY CONSERVATIVE in regards to the overall tuning, to ensure reliability, which was my #1 concern.

As I was driving back for 7 hours on the highway back to Norcal, everything was smooth as silk. No fluctuating idle. Pulls hard everywhere in the powerband. Temperature...if you remember my last post, it reached 104 degrees Celcius in traffic. This time, highest I saw (in traffic and every other condition), was 92 degrees Celcius. Every gear pulled like crazy. Even 6th gear, I was able to boost and past cars with complete ease. Got home easily, felt like driving a stock Z, just with a lot more power.

What can I say...Sam has done everything as promised, and more.

So with the 3 maps, I don't have the dyno for the low low boost...that's wastegate pressure at around 600rwhp/600rwtq.

Low boost (91 octane w/ water/methenol injection) at 14psi:



High boost (race gas w/ water/methenol injection) at 18psi:

 

Wow those are high hp numbers.

 

damn,600rwhp? my n/a is at 260whp it's like you have 3 VQ engines under your hood. any more video?

 

to get to 420 what over-bore did you use?

 

100mm bore, 90mm stroke. It's actually 4.24L. Some people like to round up to 4.3, I like to round down to 4.2.

 

Saw your car there, it's a beast man. Nice looking car. Sounded deep the couple times I heard them start it

 

Sick.

 

Thanks man. Saw your dyno charts a few threads down...now that's SMOOTH! Hope you're enjoying your car as well!

 

Great numbers. way to go!

 

Awesome.

 

Amazing... so its alot faster now since i last time i saw it then i see. good stuff GTM!

 

i cant believe you have such a beast as a daily driver.. must be so much fun.. i cant even imagine

 

think your heat issue is a result of thin walls at the water jacket? not much you can do but treat the symptoms if that is the case.

 

Nice, any all out dynos in the future?

 

So your car should really be called the 424Z TT !

 

that was brought up in the last thread I had wondering about the reasons behind the issue. But all we did was add the stronger fans, and used Fcon to control it to turn on at a lower temperature, and everything is perfectly fine right now.

 

No plans to do so at the moment. Going to let Sam do the R&D on his car since I have a budget...unlike him.

 

 

just don't score a cylynder wall, because a bigger bore is out of the question. Sleeves may be an option....but that would suck.

using an oil cooler?

 

It's sleeved.

oil cooler, power steering cooler, koyo radiator, pathfinder cooling.