Zl1 Heat exchanger and injector question

[CoveyZL1]

Current build consists of rotofab cai, kooks long tubes, catless midpipes, and corsa sport exhaust. Just ordered an ls9 cam, 2.5 upper, 100mm idler, and all necessary hardware. My question is, if my boost has naturally been lowered with the install of headers and cam, will I need injectors and a heat exchanger? This is all taking into account, I should only see a 3psi boost with the 2.5 upper. Looking for a conservative 600whp goal. Car dynoed 527whp with just the intake and full 3" exhaust. Any insight would be greatly appreciated.

[Can'tHave2MuchHP]

You will need injectors for a 2.5" upper. The percentage that the supercharger is over driven is what determines if you need injectors.

5% and 10% Over drive is safe on stock injectors on most cars
A 2.5" Upper is 18% Overdrive and is way past the safe point on stock injectors.

Grab a set of ID850s or something and go.


And as far as an upgraded HX, you'll have to tell us how you plan on driving. Road course/lots of drag racing, yes new HX, but just streeting and spirited pulls? You'll be fine with the stock one.

[CoveyZL1]

Im seeing conflicting information on this... Lingenfelter stage 1 kit accommodates a 2.5 upper with no injector update. The car won't be tracked... Weekend warrior with occasional wot runs on the highway... In Mexico of course.... Don't see the need for a hx... Not trying to be cheap, but if I'm only going to do the 2.5 upper, I again do not see the need. Thank you for the quick response btw

[CoveyZL1]

I did forget to mention, I also ordered an ls7 90mm throttle body... Any recommendations other than Id for injectors?

[Can'tHave2MuchHP]

People have had good experiences with FIC injectors, but those are the only ones that come to my mind.

And as far as the conflicting information...I do not know how Lingenfelter is getting away with that...Sure it's possible but the injectors will be WAY over 100% duty cycle even at medium-high throttle I'd guess. Scope around on some threads and you'll see people saying that ANY pulley swap requires injectors. Some cars can handle 10% overdrive on stock injectors, others can't. Some cars are hitting high 80s and low 90s on their Injector duty cycle when the car is stock. The injectors on this car are a major bottleneck, they need to be changed when almost any work is done. For the long term, definitely do injectors, and I'd highly recommend ID850 (You'll find that a majority of the ZL1 community runs ID injectors with nothing but great feedback) however FIC is also commonly used with just fine results.

A golden rule to follow IMO is, it's fuel, don't scimp on it. All it would take is one failure on a few revolutions on the engine and boom, RIP engine.


*EDIT* for golden information that you can take to the bank, call Ted Jannetty from JRE Racing, a quick google will reveal his number. He can tell you what you will and will not need.

[SSmokinSS]

Originally Posted by Can'tHave2MuchHP

You will need injectors for a 2.5" upper. The percentage that the supercharger is over driven is what determines if you need injectors.

5% and 10% Over drive is safe on stock injectors on most cars
A 2.5" Upper is 18% Overdrive and is way past the safe point on stock injectors.

I'm running a 2.50 upper on stock injectors. Runs great and not over 100% DC. Close! but not over. Dyno read 628hp. Injectors are on my short list.

Buddy is running 2.38 on stock injectors....

Upgrades are recommended, but not an absolute must have.

[CoveyZL1]

And the conflicting information continues.... I agree that I will be right on the threshold of needing injectors... I will look into the fic's and id's... But what about the heat exchanger? It seems it may be good insurance as well... Also, would you recommend a 160tstat? I've read that they're not necessary...

[Jeff_SS]

Fuel is something you should never skimp on...

[STUNNAH]

I'm running a 2.55 upper pulley with 160 thermostat on stock injectors, absolutely no problem after tune it drives better than the stock setup...Your concern would be with the cam and additional mods you are doing, you'll be getting more air which requires more fuel, so yes you should install larger injectors at this point and a thermostat...No track time on my car but I make a spirited run WOT from time to time so a heat exchanger was not needed, you may need a larger coolant tank but nothing overboard...My temp gauge moves a little past the 1/4 mark and has not gotten close to the 1/2 mark...

[STUNNAH]

Originally Posted by CoveyZL1

Current build consists of rotofab cai, kooks long tubes, catless midpipes, and corsa sport exhaust. Just ordered an ls9 cam, 2.5 upper, 100mm idler, and all necessary hardware. My question is, if my boost has naturally been lowered with the install of headers and cam, will I need injectors and a heat exchanger? This is all taking into account, I should only see a 3psi boost with the 2.5 upper. Looking for a conservative 600whp goal. Car dynoed 527whp with just the intake and full 3" exhaust. Any insight would be greatly appreciated.

You should have done the pulley with the first set of mods...You would have been close to 600 RWHP at that point...And it looks as though your tune was very conservative...Should have been closer to 550 RWHP...But that's part of the process...