When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I’m at a crossroad with my 1989 GTA. I’m putting a ZZ4 long block in GTA; the heads are ported, I have a LT4 hot cam with 1.6 RR, Edelbrock TES headers and 3” exhaust. Should I use the FIRST injection or get a HSR setup? What size injectors, I have 24lb now and at what pressure? I have an Edelbrock 70mm tb for it but I don’t like the look and how it bolts up (upside down to use factory tb cable), any other alternatives? What type of power gains should I expect? I have a Custom Prom from Scott Hansen burned for a milder setup, should I data log and burn another prom or upgrade my ECM? Should I use the hot cam or the ZZ4 cam with 1.6 RR on the intake and 1.5 RR on the exhaust? Any input would be appreciated. Thanks in advance.
Last edited by myzblubyu; 05-24-2019 at 06:37 PM.
Reason: Add another question
first>hsr idle-5K
24lbs is fine and stock pressure, any change in size or pressure needs to be done with dyno tune
use original FIRST TB they sell them separate
hot cam>zz4 no matter what rocker config.
get rid of those edelcrock headers get dyno don 1/3/4 or slp 1/3/4 headers
what ever you do you need to know what your gonna do with the car
a hot cam will have more loop at idle than the zz4
HSR will be faster at drag
FIRST will make more powa and torque down low but its useless if you cant put it to the ground slower ets your spinning off the line then you dont have the top end either, hsr easier to launch and will make more power up top for faster car
i personally like the look of the long tube runner intakes but all my cars have mid to short runner intakes to take on the new 500hp cars of today on the streets
your setup up depending on how good the tune is and if you upgrade to 1/3/4 headers should make 300-330rwhp with a HSR on it a bit less but more torque with the FIRST
I'm probably one of few that's run both intakes on the same engine (9.8:1 355 making 331RWHP with the StealthRam). Here's a cut and paste from a post I made back in 2008 with minor edits - Hope it helps
As far as intakes go,,, it's all about what you want from the car. I liked the FIRST on my old IROC,, because of the midrange boost from the longer runners. It pulled down low almost as hard as the fully ported base and "customized" SLP runners - I took the SLP runners on and off the car grinding a little,, then doing three or four vericom (g-tech) passes until the ETs and MPH leveled off. It was as "tuned" as it could be for that combination and the FIRST right out of the box performed almost a half second better.
I liked the StealthRam when I switched over to it,, but missed the midrange rush of the old TPI - although I did like how the car could hook decently on street tires,, something impossible to do with the old TPI/SLP combo,,, and how well it ran from a kick. The FIRST is middle of the road,, but that's not necessarily a bad thing. It moved the power band up a few hundred RPM compared to the fully ported TPI/SLP combo,,, but not as high as the StealthRam.
Power band wise: TPI/SLP - off idle to 5500 rpm - high-12.9s@105mph FIRST - 2000 - 5800 - mid-12.5s@107mph HSR - 3000 - 6400 - low-12.6s@108 ETs are for similar conditions with temps in the high 80s
To help with the comparison, a buddy with a 13.0 second LS T/A would pull ever so slightly away from me with the old TPI/SLP combo from a 60mph kick. I could blow his doors off with either the HSR or the FIRST - with the HSR being a steady even pull while the FIRST would really put it on him on the initial hit and kinda tapered off a bit. That same 13.0 car could hand over the TPI/SLP combo on street tires,, bad,, I could not hook the thing. Again,, with the StealthRam and the FIRST I could flat blow his doors off,,, but the FIRST was harder to hook. Like I said,, it all depends on what you're looking for. I never ran a ported FIRST on the IROC, but would have expected about a .12 reduction in ETs over the box stock FIRST with relatively minor port work / clean-up. Not that it's bad out of the box,,, it's just sized to a stock exit,, and it turns down into it. The injector bumps are also quite large and can be dang near flattened out.
I've made this statement a few times over the years and it still holds true. If I raced the car more than I drove the car, I'd pick the Stealthram - put some heat in the slicks and foot to the floor at the track. It was hard to mess up a launch. If I drove the car a lot and raced it occasionally, which I did, I'd go with the FIRST. It rolled off a little of the initial hit at launch making it a little easier to hook than the TPI/SLP combo, but it was manageable,
Another thing to consider is that the FIRST ran well with the stock MAF tune with a couple pounds added with the fuel pressure regulator and a couple degrees bump of the base timing - can't say if that would be the same with a speed density system. Regardless, the HSR requires a lot more tuning to get it to perform decently - have to add a good bit more timing compared to a long runner tune and have to mess with the tip-in tuning or it'll feel a little sluggish. Definitely need a custom tune with the HSR.
Thanks for the replies. After researching, I’m going to use the FIRST tpi. The long tube runner looks great. My GTA is just going to be a street car and might only see an 1/8 mile once or twice. If I have 325-350 Hp and over 400 torque I’ll be very pleased. I’ve bought my daughter and son a 2010 and 2015 Camaro 2lt RS and they are both faster than my GTA now. In a couple of weeks that will not be the case.
05-24-2019, 06:34 PM
