hi guys,

i am rockin an APS single turbo kit on my car, and i noticed that my car have a problem in the low-end. not a problem actually, its just not powerful enough on lower gears and RPM ( below 4000RPM ).. on the other hand. it runs very well on high gears and high RPM.

example: in uae there is an event every weekend on a drag strip. but can be used also as freestyle drag, where cars can run from roll. so i tried with a GTR 35 with upgraded Y-pipe, no tune.. ( and i am running 370whp )

so we tried first run from 2nd gear 60km/h, 3500RPM

On green light,
2nd gear end, 1 car ahead for the R35
3rd gear end, 3 cars ahead for the R35
4th gear end, i started catching up, so it became 2 cars ahead,
5th and sixth. the distanced was constant, 2 cars for the R35


then we tried the 2nd time from 3rd gear, on 105Km/h, almost 4000RPM

on green light,
3rd gear end, 1 car ahead for the R35,
4th gear, half car a head for the R35
5th grea, dead even.
and then we passed the line.

below are the mod list:

1) APS single turbo kit.
2) APS single turbo Exhuast.
3) GTM oil cooler.
4) AEM water/methanol injection kit.
5) HKS EVC5 boost controler
7) cooling mods: radiator, samco hoses, thermostat,
8) Motordyne plenum spacer.

boost level,
2nd gear, spike to 9 - drop to 7
3rd gear, spike to 10- drop to 8
4th gear, spike to 10- drop to 8
5th gear, spike to 11-drop to 9
6th gear, spike to 12-drop to 10-9.5

stock engine. stock cams,

i know that ST tend to work better on high RPM, rather than lower, but i am trying to find a way to make it better, so i thought of a set of cams that can help in making the low-end slightly better.

any advice will be appreciated, i did alot of research, but most of the threads was on built Z's and most of them was TT

anyother suggestions ( other than cams ) would be appreciated as well.


and yes am planning to go for built engine in the future... but hopefully not in the near future, my pocket wont take that much of harm as of now :P .. am about to get married.

 

Have you played with your boost controller? you should be able to get 12psi in 2nd gear and hold it rock steady. Your turbo shouldnt be running out of breath and dropping your psi.

Swapping cams is no easy take and should really be done when you are redoing the entire motor.

The FI cams I have seen only shift the power curves to the right. Maybe a NA grind might be better at the cost of high rpm power.

you are giving up almost 100hp the R35, so being that close it pretty good.

Are you brake boosting before you start the race?

 

am running on EVC 5, but it never worked for me to get it past the 9 psi mark on lower gears,

as per my research . u can never do a brakeboost with a Z. unless u lose the breaklight !!!! ..

but no i am not brakeboosting.

i have a very good deal on JWT S2 cams, but still dont want to go for them just for the sake of good deal.. i want to go for something which will return with good results. so if they will give me good results on the lowend. i will go for them, otherwise.. will just wait for your experienced advices champs

 

you can brake boost without losing your taillights.

Plenty of threads telling you how to do it. I think its switching pin 101 on and off with a toggle.

What is your target boost, 12psi or 9psi?

Can you install the cams yourself? It will cost a normal shop around 1500$ to install. I;d add a 30 shot of nitrous way before I'd mess with those cams on a stock block.

 

honestly what the person before me said about no2 is that i seen alot of people with big single turbo use no2 to hep with quicker spool of the turbo. You may want to get the no2 so you can get your turbo up to the psi you want. I honestly think that will give you AKA fake boost as low end. I think that the reason why TT dont have to worry about low end to much because of turbo size and other things (correct me if im wrong).

 

I would only get cams if you want to make more power up top. I have GTM stage ones and they seem to make decent power in the midrange and kept my power from falling off. No cams that I know of will really help you below 4000 rpms..... that said, I don't see that being your problem. You need to look at a new boost controller and get it dialed in if can't make the 5 work. You might need one that does gear based boost control like the evc6. You basically need to turn the gain up in the lower RPMs/gears That is the only thing I think you need to really do. IMHO you are not going to get what you want out of cams. And just to throw it out there, if you do cams, you might as well build the motor. You will basically be paying for about the same amount of labor to install cams.

Edit:
as far as your runs go, the closer you get to a dig, the more the R35 will pull on you. the more "from a roll" you go, the better chance you have.

 

I vote for NOS to get what you want. Cams for top end.

 

you should have gear dependent boost setting with the evc

 

i haven't been paying much attention to the aps builds but i think some were seeing faster spool by heat wrapping the exhaust.i wouldn't waste my time with cams,it looks like you put together a nice dd street package and cams would send you down the rabbit hole.

 

In General, cams that are gonna really help you down low in the rpms, are gonna kill your top end power, and vice versa......hence variable valve timing

tom

 

MY MECHANIC GAVE ME A GOOD DEAL FOR , port and polish/ install cams/ new headgasket installation. all labour work = 400$ , the cams am getting from a buddy for almost 300$. thats why i said its a good deal

i dont want to have NOS at all , i have a nos fobia. hehehe .. would like to look at alternative solutions. thanks for the advice, appreciate it

thanks Zivman. as usual, u always support me in my issues thumbs up...

i was thinking of getting EVC 6, but thought the cam deal is just too low to be negleted, thats why i thought of asking for an advice.

i believe EVC 6 got this feature, i will look into getting one.

interesting info, but dont know how accurate it is... !!!!! will research more about it.. thanks for the info.

so you mean if i get cams, my top end will be better and low end will be worst !!!!! or my top end will be better and low-end will be as is !!!!! appreciate your clarification plz.

 

Whats your rev limiter set at?

Mine @7200rpm and going at WOT i am always in the boost so no problem here.
My car starts pulling hard from 3500rpm and at 4000rpm its really on song.
What EMS are you running and what timing down low?

 

if your mechanic said he'd do cams for $400 bucks, he must have never done them before.

But for that price, i'd just do it anyhow.

either a better boost controller or a EMS that can control cam timing is another good option.

But for $400 labor, i'd have your mechanic do the work!

 

cams are not your answer

it makes no sense that your boost is tapering on such a setup - what exhaust are you running? What A/R on the turbo?

altering your stock cam timing via a retune, ceramic coating all exhaust components, including turbo hot side and manifolds, will also help low end significantly

If you trust your mechanic like family, let him do it. Otherwise if anyone gave me that price, I'd new they were in way over their head, and I wouldn't want to be the guinnea pig

 

When Forged put the cams in my car he charged me for 2 solid days of labor IIRC.

I went with Stg-II Brian Crower and as already noted it helps keep power up top to redline, cams will not help below 4000rpms.

 

Others have hinted at it, but let me just come out and say it. The low rpm band performance of your car doesn't have anything to do with what you want to achieve given what you posted in your example in the runs with the R35. How much time do you think you spent below 4k in your rolling runs against the GTR? - zero -

You lost because of a horsepower differential in the upper rpm band, because the R35 shifts faster, and because the R35 shifts without dropping boost.

As others have said, cams are not the answer you are looking for. More aggressive gearing (if traction is not an issue) and boost that increases to achieve a flat torque curve will likely help you the most. Flat shift functionality via relatively inexpensive add-on electronics is another option (check KPierson Technologies).

 

yep - while the VQ has pretty ample displacement, it's not an engine with tons of low end grunt. It's ample compared to other engines out there, but it's not a muscle car. It's a mid range engine in stock form, and a top end performer in built form.

 

I DONT HAVE EXACT FIGURES ON THE TIMING... WILL HAVE TO CHECK IT OUT. WHAT ARE YOU TRYING TO SAY, ADD SOME TIMING DOWN LOW>>>???

HE IS MY GOOD FREIND AND HE WORKED ON LOTS OF Z'S AND G'S ...

[QUOTE=ToastZ;8057630]When Forged put the cams in my car he charged me for 2 solid days of labor IIRC.

APPRECIATE YOUR COMMENTS GUYS.... SO AFTER ALL THAT, I THINK I SHOULD JUST INSTALL THE S2'S SINCE AM GETTING THEM FOR CHEAP, IN THIS CASE I WILL HAVE BETTER MIDRANGE AND UPPER RPM. AND ON THE SAME TIME. I WILL GET THE EVC6 AND GET IT TUNED PROPERLY FOR STABLE BOOST. ANY ADDITIONAL ADVICE WOULD BE APPRECIATED.

 

ya he must be a realy good friend if hes going to pull the timing cover off with the motor in the car to do the cam swap for $400.

sounds like you are on the right path now. good luck

 

If traction is an issue, then you don't want to increase your gearing, but you do want to produce a more linear horsepower curve and flatter torque curve. S2 cams will increase your midrange up to about 6500 rpms and that's it. It's a mild cam but provides some of the most usable power gains for a vq35de powered street car that doesn't see 7k+ rpms too often. It's what I have and I don't regret it. If I were to do it again, I would've gotten the C2s though to better flatten the torque curve up top and not create traction issues in the midrange.