Hp and tq switch, what would cause that?
Thread Starter
Joined: Dec 2006
Posts: 1,160
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From: New Port Richey, FL
Hp and tq switch, what would cause that? Car is 98 t56 4.10s. So this is an odd thing that maybe someone can answer. 2 different dynojets. But whp and wtq switched.
1st dyno tune session, was hot n humid time in Florida (so that's 1 variable). i was running lean at high 13s to low 14s. Made 422whp and 405wtq. Made more than i expected. Just an LS1 with 200k miles on original shortblock, SDPC LS6 Power Max Plus cam, 243 heads that i ported and fast 90 with bolt ons. With 4.10 gears chewing up 15-20whp n wtq. I feel like that's what i should've made with my stock 3.42s, but I'll take it lol
So I upgraded to 255 pump, hot wire kit and from the stock 28lb injectors to the L67. That's the only changes besides tuning and 2nd time for retune was the other day in 70 degree weather on a different dynojet.. Afr back under 13 and made 411whp and 426wtq.
Is something killing my whp? It's not a tq cam or something to where I should be making more tq than hp. Other than I know you can get a little more out of a motor leaning it out. But hp and tq switching? I've had my cars always dynoed on dynojets and they have always been pretty damn consistent. Like within +/- 1whp/wtq from 1 dynojet to another without making changes. Dyno graph is nice and smooth throughout the powerband. No weird dips etc that would alarm internal failures.
One other thing i noticed from the moment i switched to my fast 90 from my fast 78 (without retuning), is my throttle response was more "snappy" with the 78.3 So might go back to the 78 just to see if that changes or just in my head. But that isn't a variable for the more tq than hp thing. idk what to make of that..
Any thoughts?
Thanks in advance
1st dyno tune session, was hot n humid time in Florida (so that's 1 variable). i was running lean at high 13s to low 14s. Made 422whp and 405wtq. Made more than i expected. Just an LS1 with 200k miles on original shortblock, SDPC LS6 Power Max Plus cam, 243 heads that i ported and fast 90 with bolt ons. With 4.10 gears chewing up 15-20whp n wtq. I feel like that's what i should've made with my stock 3.42s, but I'll take it lol
So I upgraded to 255 pump, hot wire kit and from the stock 28lb injectors to the L67. That's the only changes besides tuning and 2nd time for retune was the other day in 70 degree weather on a different dynojet.. Afr back under 13 and made 411whp and 426wtq.
Is something killing my whp? It's not a tq cam or something to where I should be making more tq than hp. Other than I know you can get a little more out of a motor leaning it out. But hp and tq switching? I've had my cars always dynoed on dynojets and they have always been pretty damn consistent. Like within +/- 1whp/wtq from 1 dynojet to another without making changes. Dyno graph is nice and smooth throughout the powerband. No weird dips etc that would alarm internal failures.
One other thing i noticed from the moment i switched to my fast 90 from my fast 78 (without retuning), is my throttle response was more "snappy" with the 78.3 So might go back to the 78 just to see if that changes or just in my head. But that isn't a variable for the more tq than hp thing. idk what to make of that..
Any thoughts?
Thanks in advance
Last edited by FU_I_AM_UltraZ; Jan 24, 2026 at 03:49 AM.
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Joined: Dec 2017
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From: San Antonio
A before/after dyno chart would be most helpful, but it could just be the dyno set-up. Once you pass 5252rpms, the hp should be higher than tq. If it's not, then I would suspect a dyno issue.
Thread Starter
Joined: Dec 2006
Posts: 1,160
Likes: 30
From: New Port Richey, FL
I did just remember something from the retune session, my rack n pinion has been leaking and it did blow a seal on the dyno. The ps pump resvr was bone dry during last 2 fine tuning runs. Not sure sure if that would chew up 10-15whp... I'd think maybe a few whp...?
Last edited by FU_I_AM_UltraZ; Jan 26, 2026 at 11:23 PM.
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Thread Starter
Joined: Dec 2006
Posts: 1,160
Likes: 30
From: New Port Richey, FL
No fluid came near the rollers. But a dry pump i can see creating extra drag on the accessories. In the back of my mind, i just have a feeling its something with the china 90mm tb or the fast 90 intake. Like the internal runners having some odd issue. I have a dorman LS2 I'm going to swap on before going back to my FAST 78.
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Verdad Gallardo No fluid came near the rollers. But a dry pump i can see creating extra drag on the accessories. In the back of my mind, i just have a feeling its something with the china 90mm tb or the fast 90 intake. Like the internal runners having some odd issue. I have a dorman LS2 I'm going to swap on before going back to my FAST 78.