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FP 68hta, no info is making my head hurt

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Spector5

10+ Year Contributor
274
6
Jul 31, 2011
holland, Michigan
So I've been trying to put the pieces of the puzzle together of what fuel pump, fuel, & fuel injector size to run with this ported 68hta. Older 68 that they claimed (47lb/min).

Soooo.
A. Still no compressor map after all these years for the 68

B. Every thread seems to be a e85 injector size conversion. which I'd have to run 1200+ with the 47lb/min it produces. However, I only "plan" to run premium.

C. I've seen this turbo pushed to 36psi on e85. obviously, I have zero plans of that much boost.

Mods:
FP ported 68hta internal wastegated
Fp manifold
Walboro 255 hp
Fic750cc
1g Stock fuel pressure
Greedy type s bov
Ets 7" fmic
Megan o2housing
3" Megan down&test pipe
3" thermal r&d cat back
Ecmlink w/ speed density
(That's the mods that I can think of that will have an effect)

So my question is, with no known compressor info., on premium fuel, with my set up either

A. With the current fuel setup, what is a safe reasonable psi to run at?

B. What would be my optimal fuel system setup on premium to get the full potential out of the turbo.

C. Is my injector size & fuel system sufficient enough to safely run this turbo at all?

From what I've gathered, the turbo flows 47lbs/min on the compresskr. However, many have stated they left the hot side too small and isn't efficient enough. Which one member complained of surge at 29psi due to this efficiency issue.

Starting to regret buying this turbo as getting info on it is worse than pulling teeth.

I'm still trying to learn how to choose parts and put all the systems together efficiently and safely.
 
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@gofer is probably pushing this turbo harder than anyone else I'm aware of. So, let's use his car as a test case.

IIRC, he's logged just over 50lbs/min on his 68HTA. So let's start with that. If you roughly estimate 1lb/min of airflow = 10hp, you're looking at 500hp. But, that's probably not a likely power level on the 68HTA V1, especially on pump, so, lets estimate 400hp, which is closer to being attainable.

Considering the information above, plug some estimates into a calculator and see if you've got approximately enough injector: http://fuelinjectorclinic.com/flow-calculator

If you plug 400hp into the calculator while assuming a 43.5 BFP @ 80% IDC, you get 787cc/min for the required injector size.

So, your 750cc injectors would probably put you close to where you'd want to be on pump gas. Now, you can lower boost, increase fuel pressure, increase injector size, or even run the injector at a higher duty cycle (although not recommended) if you're running out of fuel. Ideally, getting an injector that gives you some cushion, and maybe even room to grow is preferred.

As far as what's the best boost level to run on that turbo, that's completely dependent on the setup. As mentioned above, this is where the cushion/room to grow comes into play. It's much easier to get an injector that will support the turbo at peak airflow, rather than lowering boost to meet fuel requirements.
 
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Thank you!, finally a straight forward no b.s answer.

The biggest down fall is I am kinda stuck tuning to my fuel injector size. I bought all these parts many years ago, and now just putting it together(zero extra funds). I failed to do the proper research, and ask the right questions when I ordered all my parts years ago. :(.

I guess for now, I will have to use the chart you gave and others I found to keep my 750's within my 80% IDC ceiling.

Could be gopher be the car I seen at boostin performance? This guy was at 36psi @ I think 530+who on a 68hta & e85
 
Well, also keep in mind that estimate is based on fuel to support 400hp. I'd say 400hp on pump gas via a 68HTA V1 is pushing it. Gofer, for example, is making a bit over 400 on E85. I think you'd be looking at the 300-350hp range. At that power level, your injectors would be adequate.
 
Yeah I was playing around with a few other fuel injector calculators. They were within the ball park of eachother. It is nice to get a round about idea, but have yet to find one that you plug in turbocharger numbers or air flow numbers to get a fuel injector size, fuel pressure, etc..

I'll keep researching around, thank you for your time.
 
@Kapok6 Yeah pretty much LOL

I'm running 850cc injectors on the v2 68hta and I'm only hitting about 60% IDC at 28psi and seeing roughly 48lbs/min so 750s should be fine with the v1, I am actually switching over to the V1 68hta this winter. The only thing I do not see on your list @Spector5 is an AFPR, which might be a good idea so you don't overrun the stock FPR, Beyond that GST with PSI is right on point
 
I doubt you will ever see a compressor map for an FP turbo.

You never see them because they don't exist for 99% of the turbos they build.
 
I've been told otherwise.

By who?

I guarantee FP isn't operating on a level where they can provide that level of research, development, and testing themselves. So, unless they are sending their turbos out to be tested (which I also doubt), maps for the turbos they build don't exist.

If FP wasn't going to advertise the maps, what would point of testing the turbo and creating a compressor map if it's not used to educate customers in order to further sales of the turbo itself? That testing costs money, so unless it was being done to make the company more money, that's not a terribly smart business move.

I can't say for certain they don't exist, but I don't see the point in FP hiding that kind of data from it's customer base. It doesn't make any sense.
 
Thanks for tagging me, Brett. I just realized you're up in Annapolis, I was just up there a few weeks ago visiting an old Navy buddy. :ohdamn:
So my question is, with no known compressor info., on premium fuel, with my set up either

A. With the current fuel setup, what is a safe reasonable psi to run at?

B. What would be my optimal fuel system setup on premium to get the full potential out of the turbo.

C. Is my injector size & fuel system sufficient enough to safely run this turbo at all?

From what I've gathered, the turbo flows 47lbs/min on the compresskr. However, many have stated they left the hot side too small and isn't efficient enough. Which one member complained of surge at 29psi due to this efficiency issue.
If I were tuning your car I'd recommend not running more than ~ 21psi because I don't see any ARP head studs in that mod's list. My first dyno session with this turbo I was lifting the head at 23psi on stock 7-bolt head bolts. The fuel upgrades you've made will be plenty to support the HTA68 v1 on premium, the only thing I recommend is a fuel pump rewire since I don't see that listed.
 
You guys have been a world of help!

Sadly, I am still running the stock 1g FPR. Which after more research, I shouldn't be so focused on injector size, but be able to get a little more pressure out of my system. May take out a bank loan to get an AFPR(totally kidding). Would it be safe to adjust to the 2g fuel pressure? I noticed moving the fuel calculator to the 2g pressure really opens the ceiling and gives me a bit more cushion from fuel cut.

I can understand from a business sense why FP wouldn't put out a compressor map and/or they just don't have the resource's to.

However, I'm just at a point were I'm trying to absorb and actually learn how to calculate the air flow, fuel system requirements, etc. for my own personal knowledge. I've spent most of my "DSM life" sitting on forums and choosing parts that everyone else seems to be running. Which as you can see puts me in this predicument.

Also, with such a thrown together setup. I like most that don't understand or do not know the proper math end up with repeated threads.

Nothing personal towards anyone here. However, throwing parts the way I have with no clear understanding is getting old. On the flip side, its getting old that I still have to fall back on everyone else because even the parts I do get from "reputable" company's give such little info.

Sorry for the headache of a post, my phone doesn't like this website and trying to qoute doesn't seem to work.
 
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By who?

I guarantee FP isn't operating on a level where they can provide that level of research, development, and testing themselves. So, unless they are sending their turbos out to be tested (which I also doubt), maps for the turbos they build don't exist.

If FP wasn't going to advertise the maps, what would point of testing the turbo and creating a compressor map if it's not used to educate customers in order to further sales of the turbo itself? That testing costs money, so unless it was being done to make the company more money, that's not a terribly smart business move.

I can't say for certain they don't exist, but I don't see the point in FP hiding that kind of data from it's customer base. It doesn't make any sense.

By an FP employee.
 
A buddy of mine with a 2g and v1 68 had his car tuned at DynoTech Tuning up in MA. With an Evo3 intake manifold, bigger throttlebody, stock cams, 9:1 compression, and a the ETS "street" intercooler, he put down 312 to the wheels on a mustang dyno. Car was tuned on DSMlink and Speed Density.
 
Sadly, I am still running the stock 1g FPR. Which after more research, I shouldn't be so focused on injector size, but be able to get a little more pressure out of my system. May take out a bank loan to get an AFPR(totally kidding). Would it be safe to adjust to the 2g fuel pressure? I noticed moving the fuel calculator to the 2g pressure really opens the ceiling and gives me a bit more cushion from fuel cut.
If your 750cc injectors came with paperwork from FIC you'll notice they were flow tested at 43.5psi, which is also 2g bfp. The reason why you're seeing the ceiling raise is because by increasing or decreasing fuel pressure it effectively changes the amount your fuel injectors can flow too. The stock 1g base fp is 37psi so those 750's are actually flowing ~ 692cc, which is considerably less but still enough to support what a HTA68 v1 on pump gas. By bumping fuel pressure to 43.5psi (stock 2g bfp) they'll actually flow close to what they're rated for at 750cc.

That being said, I wouldn't be surprised if you're experiencing a bit fp overrun at idle with your 255 HP since you're still using the stock fpr. Switching to a afpr will allow you control idle fuel pressure, setting it to what you want, and guarantee that it's rising 1:1 with boost as it should. Not 100% necessary to support the turbo and current setup but still not a bad idea...
 
I'm going to get a AFPR before I move any further to get psi up to 43.5(gives me a reason to install my FIC fuel rail) and it will relieve the possibility of fuel overrun at idle. That way it will take away one headache and I can tune knowing I'm flowing 750cc for what they are.

Also, keep my turbo @ 20psi for now until I can dig into the Engine. There is still so much I need to verify from the previous owner as he claims the engine was rebuilt with a 2.3 stroker, and supposedly already has ARP head studs... No paper work for any of this. So that's my fault for not asking for the paper work and I am taking it all with a grain of salt.

For the future, I'll jump to 850cc+ inj. Because after going over the math and comparing it to the turbo I have. I personally believe with even the little data I have, the 750cc just won't give me any room/cushion. Especially, will never come close to supporting the turbo @ it's efficiency range.
 
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For the future, I'll jump to 850cc+ inj. Because after going over the math and comparing it to the turbo I have. I personally believe with even the little data I have, the 750cc just won't give me any room/cushion. Especially, will never come close to supporting the turbo @ it's efficiency range.

I feel like from this post you hadn't really read what Gofer and I were trying to say. Almost maxing out my v2 68hta I'm not stressing my 850s. I feel like with a v1 750s would be plenty sufficient unless you go e85.
 
I apologize if you feel I have not taken your experience and knowledge into account.

However, I understand with the 750cc injectors the car can safetly be run. Taken into account to hit my HP mark I planned for this car on this turbo. Even if I were to adjust fuel pressure to 43.5psi, keep my injectors at 80% DC I would need 780 +. If I were to squeeze 85% DC I would be at my very highest limit with these injectors.

I feel there would be zero room for growing, and actually there would be more left in the turbo. So with my current set up even on Premium, I'm still short changing myself.
 
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The HTA68 v1 is capable of flowing 47-50lbs/m, just because it's capable of it doesn't mean you'll even come close to that number running 91oct. I'd be surprised if you saw anything above 44lbs/m on 91oct which would be right at 80% IDC.

If you still want to upgrade from your 750's then don't grab an 850cc injector if you're wanting room to grow. You live in MI where E85's on every corner so at least upgrade to a injector that can support the HTA68 if you decide to run E85, like a FIC 1120 (or equivalent).
A FIC 850 is $315.00 for a set and the FIC 1120's are $365 for a set, spending that extra $50 is well worth it because it leaves the table open to running E85 if you decide you want to push the HTA68 to 450whp.
 
^^^ What he said. I apologize if I misread what you had said Spector but I thought you were only planning on running around 20psi, which wasn't going to stress your current injectors. Gofer is right, if you do plan on going bigger just skip the 850s and get something 1000+ and be done with it.
 
That's a great point, I have yet to decide if e85 is a bath I want to go downjust yet, but I will always keep that option open. I can barely wrap my head around everything to setup the car right on premium, LOL.

All honesty, I was looking to make 400hp at the crank. I understand setting a goal and building around that goal. However, I'm at a point where talking HP numbers is just HP numbers. I'm trying to be more concerned on learning how to put together a complete efficient package with HP a secondary concern.

Seems a bit counter productive, but I really need to stay focused on learning how to calculate or have a clear understanding of fuel, air, etc... So that in a year or two if my goals change. I'm not back on here starting all over again. Making the same thread, questioning every option or part I decide to choose.

I'm pretty sure it's typical me trying to learn years of knowledge in two days. I tend to do that a lot.
 
Well I think what everyone is trying to tell you is that plans change in a hurry and if you leave room to grow now it will save you money later one. We've all been there where we thought 300hp would be enough, then 400hp but the fact is most people get the bug and just keep going.

HP is not a secondary concern. It really is the starting point when sizing a fuel system. I think your original question has been thoroughly answered. Do you have enough injector to support the 68HTA in your current configuration on pump gas? Yes because you will be in the mid 40's on airflow, however when you decide to make a change in your combination and you will, either to go E85, run a larger turbo, cams, whatever it may be, you will need larger injectors.

So if you are going to buy them now, just get it out of the way and know your not running too much duty cycle. Then buy MUCH larger than you currently need to give yourself room to grow. Then when you "calculate" your fuel system later on to go with your new air flow number or change of fuel tyepe, you will find that you still have enough injector. We can only say this so many ways.
 
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