How Much Boost Can I Run?

[davo345]

i will be getting the stage 2 star kit and i was wondering how much boost i would be able to run safely under 2 conditions:

1. the kit as it comes without any fuel mods

and 2. with 310cc injectors and a SFMU

let me know! thanks!

dave

 

[slodsm]

Safely, standard number is ten lbs, not due to fuel, due to rod weakness, I have been told time and time again that they will start to give out at 13 lbs. I myself didn't care and ran 12 lbs every day for a few weeks back and forth to work just to see if it would hold, I had no problems, Using the Cartech and Missing link, I was seeing EGTs at about 1480 on a hard pull in 3rd to redline. I cranked it back down to ten last week but I will probably go back up to 12 again. I had no detonation and such, just didn't want to crack a stock injector so I am ordering larger ones before I crank up the pressure again. I am really looking for an excuse to buy a new bottom end but I think it will be more than 12 to make that happen.

 

[davo345]

hmm...thats interesting...all of the other replys ive gotten about this issue seemed to be a bit more conservative. some people are saying that WITH fuel modification a max of 10 psi. i am getting different answers from everyone! ahhhh HELP!

 

[siueclipse]

you can run up to 10psi, thats it. you shouldn't even run 10psi every day or else youll be building your bottom end soon.

 

[slodsm]

once again, its all a matter of opinion, fuel, and tuning. you can only run a 75 shot on a stock block or it will blow is all over the net. Anyone try experimenting? I did. in 99 till mid 2000, I ran a 125 shot on a fogger kit on a 4 banger, never evn detonated. Just have to know what YOU are capable of, manufacturer's are only going to tell you so far, then they will stop to keep them from being liable. hahn made 350 horses on a stock bottom end before it gave out. its all about you, not so much the car. Sure it has its limits, they all do but if you have access to a dyno and tuning tools, the results will be different with proper air fuel and timing on anything. Engine will take more abuse when tuned properly and not beat on.

 

[davo345]

thank you, sir

 

[Kirby]

Originally posted by slodsm
Safely, standard number is ten lbs, not due to fuel, due to rod weakness, I have been told time and time again that they will start to give out at 13 lbs. I myself didn't care and ran 12 lbs every day for a few weeks back and forth to work just to see if it would hold, I had no problems, Using the Cartech and Missing link, I was seeing EGTs at about 1480 on a hard pull in 3rd to redline. I cranked it back down to ten last week but I will probably go back up to 12 again. I had no detonation and such, just didn't want to crack a stock injector so I am ordering larger ones before I crank up the pressure again. I am really looking for an excuse to buy a new bottom end but I think it will be more than 12 to make that happen.

Your right it will take 13-14....
So here we go: The 13psi theroy was proven by tommyboy on 2gnt. He droped in forged wiseco pistons and used stock rods, repeatedly bending them at 13psi. 12psi was no problem, 13 is where they bent. This was with properly tuned fuel as well. As for my opinion, with the stock injectors I would not go past 8psi on the star kit. It is a fuel issue that keeps you from going up with a star kit unless you handle the fuel. When I was at 8psi on my star stage 2 I was well into the hundreds on my fuel pressure, the stock injectors were not made to do that. If I had gone up to 10psi I would have been into the 130's or higher on fp. That's not my idea of saftey. You have to remember slo that the t3t4 is different from a small 16g. I would not put that t3/t4 past 10 psi without some fuel mods like you mentioned above. If you buy the star stage 2, keep it at 8psi till you are able to do the fuel then you can go up to 10psi. I would also like to say the rods are not the only thing keeping you from running higher psi on the stock internals. Piston ring landings have cracked on guy's, and the piston rings have fried on them, pistons have cracked and so on. Mostly from lean conditions due to incorrect fueling. So the rods are not your only limiter. As for you Slo you are running RICH AS HELL if your EGT's are that low on a 3rd gear pull to redline. You need to lean that out a bit to get full power, but if you do then you will be pushing it. Also what are your fuel pressures with your setup? Always remember guys the power per psi ratings of the Hahn turbos and the star turbos are very different, esp. when you get into the large e trim ballbearing turbos. I also don't remember seeing anywhere that the hahn crew made it to 350HP on a stock bottom end. The most I have seen them say is 250-275.

 

[slodsm]

Hey Kirby, you are absolutely 110% right on the injectors, they are not meant for that and will start to crack when they see that kind of pressure over a period of time, how long, I am not sure. I don't want to know. Thats why I cranked it back down some. As for my fuel tuning, I honestly tried to go down, here is the problem, when I lean the motor out any, it starts to lag between 3k and 4.5k, not turbo lag, its in boost, the motor just does not pull hard at all. When I richened it back up to the setting it is at now, it starts to pull hard at about 3200 and will stay at nice EGT's and no hiccups. right now, the car has not been on the dyno. I am waiting on two parts. Injectors and cam gears. Then she is headed straight there to get a nice tune and see what will happen. I will also most likely use an AFC for minute adjustments as well. they are on the shelf here though so no waiting. Lastly, yeah, hahn advertises 250 to 275 where he is trying to sell the kit but I went through and read all of his R&D and shit on his site and that is where he put the 350 hp is where the rods start to go. (wish I had the money to test like that, or just the wife who would let me spend it ) but anyways, you are right about the T3/T4 setup as well. I only know one guy running one here where I am, he however ran 10 psi non intercooled for a good while and when his let go, it was the head gasket. Only other mods were AFC and 310cc injectors. decent times for a non intercooled kit too because you know that air had to be hot as hell but he was running 14.4's with the car. Davo, on his mention of CFM difference between the two, I would probably stick to ten at the most on that car until you get some other mods. You will not be unhappy at that either. Happy boostin.

 

[davo345]

very very nice. about how much will i putting out at around 7 psi until i get those other fuel mods?

 

[slodsm]

I really couldnt tell you man, I just know when you go from a NT car to the turbo setup, its a hell of a change. I don't even bother guessing hp but when I started mine for the first time with a turbo at 6psi, I was so damn happy when the boost came up, was like a tottaly different car.

 

[davo345]

well, thats good enough for me !

 

[slodsm]

Ar eyou going to put it on your self davo? It will take you wo days probably with the shitty instructions but some guys over at 2gnt have hahn instructions online, you can use them for a lot of it. Also, if you do decide to do it yourself, it will help you in the long run because you will know how everything goes together and its easier to trouble shoot when it screws up on you.

 

[davo345]

yeah me and a few buds are gonna install it together. i printed out the hahn instructions already too