Strange Dyno numbers, Advice requested.
Strange Dyno numbers, Advice requested. 94 Z28, Fresh rebuilt 355 LT1, 227 Crane Cam, LE1 Heads, 1.6RR, Kooks headers, full catless Borla exhaust with cut outs, Vortech supercharger with 6.5Lbs pulley, 42lbs injectors, through a 3200 Edge stall, Line locks, Fireball, full suspension....blah blah blah. Made 302hp 422tq. Dyno operator noticed the fuel presure was dropping off to 35 and recomeended a new 255 pump be installed. Any reason why the Hp and the Tq are so far apart. Something seems to be a miss. I was thinking the HP/Tq would be in the low 400 range. Any suggestions...advise?
FI applications can produce massive torque. In some case, moreso than horsepower. Probably would be a good idea to post up the graph? Do you know what your air/fuel was during your pulls?
Ok I will get the sheets from the shop tomorrow and post. I was not present for the runs. He said at cruise it was around 12-1 and a full stride it was 15-1 and they shut it down when it had one spike to 17-1. I am running a Walbo 225 now. Looking up online... AEM and Areomotive stand out as being good options. The engine alone should put out 325whp with anther 100whp coming the way of FI. Seems like more then a fuel pump issue. Could it be a faulty injector? At my hp level, the fuel rails should offer plenty of flow.
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On The Tree
Joined: Nov 2017
Posts: 157
Likes: 9
From: Oshawa, ON
The consensus online seems to be that a 255 lph fuel pump will support up to 475-500 whp, so that would seem to be sufficient for your setup.
As for having a bad injector, I know my tuner can "turn off" specific cylinders in his software. He used this on my car to try and troubleshoot an underpower condition (although in my case it didn't show anything, ended up being a clogged muffler). If each cylinder is working correctly then you should see a noticeable difference when turning it off. If you see no difference then it would indicate an issue with that one.
As for having a bad injector, I know my tuner can "turn off" specific cylinders in his software. He used this on my car to try and troubleshoot an underpower condition (although in my case it didn't show anything, ended up being a clogged muffler). If each cylinder is working correctly then you should see a noticeable difference when turning it off. If you see no difference then it would indicate an issue with that one.
Ok I will get the sheets from the shop tomorrow and post. I was not present for the runs. He said at cruise it was around 12-1 and a full stride it was 15-1 and they shut it down when it had one spike to 17-1. I am running a Walbo 225 now. Looking up online... AEM and Areomotive stand out as being good options. The engine alone should put out 325whp with anther 100whp coming the way of FI. Seems like more then a fuel pump issue. Could it be a faulty injector? At my hp level, the fuel rails should offer plenty of flow.
Why not fix the issues you have and then chase HP numbers.
I would run two walbro 255s in tank and one triggered off when you get into boost.
Piston soup, that made me laugh but you are right. They drove it on the Dyno as part of the break in and once it seemed to be good they tested to see output. We obviously will not Dyno again until we find the cause and at minimum swap out filters and pump. Could it be anything else other than fuel pump?
TECH Veteran
Joined: Apr 2008
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he has a stock in tank pump + the external one Vortec added
Get the fuel issues sorted out and your peak HP should be around 350 at the wheels.
KW
And that is why I thing something else is going on. 350 at the wheels for a h/c boosted car is very low. Should be 325whp with mods na. Or am I mistaken?
In that case, even your torque numbers are a bit low.
But it's nothing that a 255LB pump and a good dyno and street tune can't cure.
KW
I have other decent hp cars but this one has been a long project and it was my ride to my wedding 20 years ago. I want to do period correct mods and get as much as I can. I know it is no LS7.
No point in any questions until you get the FP replaced. That is dangerously lean for a boosted setup.
New FP - I would go dual 255s or a 340+bulkhead upgrade at minimum - then finish the dyno tune to see where you are.
New FP - I would go dual 255s or a 340+bulkhead upgrade at minimum - then finish the dyno tune to see where you are.
Has a brand new fuel pump in there now that came with the kit. Must be defective.