Help solving somewhat dissapointing low Dyno results
Thread Starter
Intermediate
Joined: Jul 2003
Posts: 32
Likes: 0
From: carrollton tx
Help solving somewhat dissapointing low Dyno results
Hey all!!
I could really use some help figuring out the reason for my perceived low Dyno performance.
It only made 400.5whp and 371.20wtq on a dynojet
The engine builder and myself were expecting closer to 450whp and 425wtq
At first glance does anything Ive done stand out as a possible problem?
Do I have a bottleneck somewhere?
Is the tune possibly not aggressive enough? I had it dyno and street tuned by a well known shop.
Is there a specific part(s) Im using that's keeping the max power limited?
Or,
do these results look about right for the mods I've done?
Its not a daily driver. I do plan on tracking it on average a couple times a month but mostly use it for screwing around, running errands on the weekend and as a project I can work on and enjoy.
Thanks for any help
-Mark
2000 c5 Coupe Automatic 18,500 miles
Air/fuel
Engine/Valvetrain
Exhaust
Transmission/ Drivetrain
Wheels/Tires
Suspension/Brakes
Misc
I could really use some help figuring out the reason for my perceived low Dyno performance.
It only made 400.5whp and 371.20wtq on a dynojet
The engine builder and myself were expecting closer to 450whp and 425wtq
At first glance does anything Ive done stand out as a possible problem?
Do I have a bottleneck somewhere?
Is the tune possibly not aggressive enough? I had it dyno and street tuned by a well known shop.
Is there a specific part(s) Im using that's keeping the max power limited?
Or,
do these results look about right for the mods I've done?
Its not a daily driver. I do plan on tracking it on average a couple times a month but mostly use it for screwing around, running errands on the weekend and as a project I can work on and enjoy.
Thanks for any help
-Mark
2000 c5 Coupe Automatic 18,500 miles
Air/fuel
- -Vortex rammer air box
- -WCC larger Air Bridge with silicone couplers
- -Stock MAF (screenless)
- -Stock Ls1 throttle body (Ported & Polished)
- -Throttle body Spacer
- -Fast ls1 TB adapter
- -Fast LSX 92mm
- -Z06 Fuel injectors 30lb??
- -Stock Fuel Rail
- -New stock replacement driver side fuel pump and filter
Engine/Valvetrain
- -Trick Flow GenX 220 "Fast as cast" Heads fully assembled with titanium retainers and exhaust port matched to headers.
- -Comp Cams 228/232 .588/.595 LSA 113 camshaft
- -Durabond camshaft bearings
- -Clevite P Main bearings
- -Clevite P Rod bearings
- -stock pushrods
- -Comp Cams Retro-fit Rocker Trunion kit
- -LS7 Lifters
- -LS7 Lifter Trays
- -Cloyes Billet Double-Roller timing set with zo6 chain
- -Melling 10296 High Volume High Pressure pump (Ported)
- -ARP-Pro Connecting rod bolts
- -ARP Head Bolts Pre-2004
- -Powerbond 25% underdrive balancer
- -New crank bolt
- -New NGk spark plugs
- -New Zo6 plug wires
- -Mezier Electric Water Pump w/160 deg thermostat
- -Ls6 coolant pipe upgrade
- -Billet Power Steering pulley
- -Samco silicone engine hose kit
- -New alternator
- -New optima battery
- -All new belts/gaskets/seals
Exhaust
- -LPE 1 3/4" Stainless Long Tube Headers
- -Gutted Cats
- -Magnaflow X-Pipe
- -Borla Stinger dual exhaust
Transmission/ Drivetrain
- -Stock transmission
- -Stock Converter
- -3.73 differential
Wheels/Tires
- -Iforged Aero 18x9.5 Front
- -Iforged Aero 19x11 Rear
- -Mickey Thompson Street Comp 275/35/18 Front
- -Mickey Thompson ET StreetII 305/35/19 Rear
Suspension/Brakes
- -Baer Eradispeed 2 piece drilled slotted front rotors
- -Baer Eradispeed+1 2 piece drilled slotted rear rotors
- -Zo6 Front and rear sway bars with metal endlinks
- -Bilstein Sport shocks
- -Polyuerethane upper/lower control arm bushings (Fr and Rr)
- -Stock FE1 Springs
- -Lowered (bolts removed in front, longer bolts in rear)
Misc
- -Sound proofing of rear wheel wells and inner rear bumper
- -Export Tail Lights w/ flush mount kit
- -HID projectors w/ Halo
- -HID Fog lights in stock housing
- -Summit Pro Torque "Mini" Starter
Melting Slicks
Joined: Jul 2004
Posts: 3,092
Likes: 120
From: orlando florida
St. Jude Donor '15
The heavy wheels and 3.73 gears don't help dyno numbers. Here's my results back when I went from 3.23 to 4.10 gears in my 2000 formula
Last edited by mrr23; Aug 7, 2014 at 12:01 PM.
Safety Car
Joined: Jul 2004
Posts: 3,904
Likes: 29
From: Vancouver Washington
The automatic and the 3.73 gears aren't helping. Other than that you might check and see if you're fuel pump is keeping up with the mods on your engine. I had to go to a Lingenfelter pump to get my similarly modded Z to 450 rwhp. You'll get it sorted out. 
Pro
Joined: Nov 2006
Posts: 627
Likes: 33
From: Omaha NE
I think that is pretty much right on for your mods and it being an auto. People telling you 450rwhp with those mods through an auto is pretty misleading. You would probably be in the 430 rwhp range with a stick. I would suggest upgrading to a 90mm TB. No point in having a fast 92 with a tiny stock 78mm TB. LS2 tb and adapters are cheap and very easy to install.
I'm not sure about the LPE headers but I'm guessing they're older and leave some room on the table for improvements. I would look into getting a set of super pro 1 3/4" LG's or 1-7/8" AR or Kooks headers.
As others mentioned the 3.73's make the car caster but on a dyno only situation they're robbing HP.
You could eventually have the heads fully CNC'd as well. Cam seems fine. I wouldn't be too worried. I bet on the strip if your car hooks you would run right along side if not beat a 450 rwhp stick car.
I'm not sure about the LPE headers but I'm guessing they're older and leave some room on the table for improvements. I would look into getting a set of super pro 1 3/4" LG's or 1-7/8" AR or Kooks headers.
As others mentioned the 3.73's make the car caster but on a dyno only situation they're robbing HP.
You could eventually have the heads fully CNC'd as well. Cam seems fine. I wouldn't be too worried. I bet on the strip if your car hooks you would run right along side if not beat a 450 rwhp stick car.
Platinum Supporting Dealership
Joined: Jul 2014
Posts: 722
Likes: 336
From: Rochester New York
Sounds accurate to me. You have a substantial gain in power, most of the mods you have listed won't contribute to any more power anyhow.
The heads/cam/headers/and gears are your only real power adders. Putting down 400whp in an automatic transmission C5 is nothing to be dissapointed with.
Expect 20% drivetrain loss with an auto, so you're at 480 hp.
The heads/cam/headers/and gears are your only real power adders. Putting down 400whp in an automatic transmission C5 is nothing to be dissapointed with.
Expect 20% drivetrain loss with an auto, so you're at 480 hp.
Thread Starter
Intermediate
Joined: Jul 2003
Posts: 32
Likes: 0
From: carrollton tx
I should add a little back history on the car.
In 2004 I had it dynoed with the following bolt-ons
Vortex cold air
Ls6 intake
borla stinger
Lpe headers
3.73 gears
Predator performance tune
Dyno Results 327whp and 329.4wtq
Car sat in the garage from 2005 until april of this year (long long story)
Removed the engine and had it disassembled, cleaned, and reassembled with the new cam and other engine parts plus added the rest of the bolt-ons from the list.
Once I put car back together it barely idled in park and would die coming to a stop at stop signs. However, at wot with the old predator tune my car was powerful and more torque I knew what to do with.
Then I took it to get tuned and dynoed. I get the car back with my dyno results and the car feels very tame compared to the tune it had when I dropped it off. It doesnt have the low end gut punching torque anymore, shifts slow and soft. Drives great but I didnt just spend $1000's on performance parts for a cruiser. Before the dyno tune I was breaking the ET streets loose from a stop and chirping them when shifting into 2nd. Now it drives fast and boring.
All those upgrades plus a tune only got me an additional 40wtq?
In 2004 I had it dynoed with the following bolt-ons
Vortex cold air
Ls6 intake
borla stinger
Lpe headers
3.73 gears
Predator performance tune
Dyno Results 327whp and 329.4wtq
Car sat in the garage from 2005 until april of this year (long long story)
Removed the engine and had it disassembled, cleaned, and reassembled with the new cam and other engine parts plus added the rest of the bolt-ons from the list.
Once I put car back together it barely idled in park and would die coming to a stop at stop signs. However, at wot with the old predator tune my car was powerful and more torque I knew what to do with.
Then I took it to get tuned and dynoed. I get the car back with my dyno results and the car feels very tame compared to the tune it had when I dropped it off. It doesnt have the low end gut punching torque anymore, shifts slow and soft. Drives great but I didnt just spend $1000's on performance parts for a cruiser. Before the dyno tune I was breaking the ET streets loose from a stop and chirping them when shifting into 2nd. Now it drives fast and boring.
All those upgrades plus a tune only got me an additional 40wtq?
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Brett Foote
Pro
Joined: Nov 2006
Posts: 627
Likes: 33
From: Omaha NE
Through an auto yes.
You gained 73 rwhp and 41 rwtq. Pretty much spot on for adding the heads, cam, and intake that you did with everything going through an auto. Those heads are good but nothing special since they're still as cast. Again I personally think you left some on the table reusing the 78mm TB.
Can't comment on the tune and driveability stuff. You'll have to take that up with your tuner. Sounds like the previous tune was seriously aggressive. Keep in mind that is great but breaks stuff faster. With as bad of a rap as tuners can get when cars break shortly after visiting them I'm guessing he turned everything down so it lasts longer. That is just speculation though. Call him back and tell him you want everything turned to kill. I'm sure he will oblige after giving you a few warnings about longevity. IMO your car is pretty much right where it should be.
Edit: Did you have the heads milled at all to bump compression? Are you sure you didn't actually loose compression by going to a bigger chamber on those heads? I'm not super familiar with the details of them off the top of my head.
You gained 73 rwhp and 41 rwtq. Pretty much spot on for adding the heads, cam, and intake that you did with everything going through an auto. Those heads are good but nothing special since they're still as cast. Again I personally think you left some on the table reusing the 78mm TB.
Can't comment on the tune and driveability stuff. You'll have to take that up with your tuner. Sounds like the previous tune was seriously aggressive. Keep in mind that is great but breaks stuff faster. With as bad of a rap as tuners can get when cars break shortly after visiting them I'm guessing he turned everything down so it lasts longer. That is just speculation though. Call him back and tell him you want everything turned to kill. I'm sure he will oblige after giving you a few warnings about longevity. IMO your car is pretty much right where it should be.
Edit: Did you have the heads milled at all to bump compression? Are you sure you didn't actually loose compression by going to a bigger chamber on those heads? I'm not super familiar with the details of them off the top of my head.
Last edited by blackdak318; Aug 7, 2014 at 05:20 PM.
Thread Starter
Intermediate
Joined: Jul 2003
Posts: 32
Likes: 0
From: carrollton tx
I had 853 heads which are 66.67cc. The trick flow 220 heads my car currently has are 64cc
Le Mans Master
Joined: Mar 1999
Posts: 6,029
Likes: 85
From: Palm Coast, FL
also bottlenecking:
-Stock MAF (screenless)
-Stock Ls1 throttle body (Ported & Polished)
-Throttle body Spacer
-Fast ls1 TB adapter
nice build by the way
Thread Starter
Intermediate
Joined: Jul 2003
Posts: 32
Likes: 0
From: carrollton tx
[QUOTE=
nice build by the way[/QUOTE]
Looks like I'll be addressing the maf, and throttlebody setup right away. What size maf and throttle body and where is the best place to get them?
As for the heads I'm stuck with them. Should I have them milled to 60cc or less? Port and polish?
Thanks for the help and compliment!
nice build by the way
[/QUOTE]Looks like I'll be addressing the maf, and throttlebody setup right away. What size maf and throttle body and where is the best place to get them?
As for the heads I'm stuck with them. Should I have them milled to 60cc or less? Port and polish?
Thanks for the help and compliment!
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
if you have the stock small maf I would upgrade to the 01+ z06 maf, you might have to do a little work with the wiring since the iat is in the maf on 01+ models and if yours is stock then you have the iat in the side of the bridge... I would also get a 90 mm tb and a racetronix pump/harness... do you know what your injector duty cycle is?... mine were close to being maxed at 420rwhp so you might just check for peace of mind... I doubt all of these things will get you to the 450 mark but they are small changes that will help in the long run and all of the grunt work has already been done
Drifting
Joined: Feb 2010
Posts: 1,720
Likes: 38
From: Colorado
seems right'ish. for comparison sake, i did my own port/polish (i've done a dozen or so heads now, 3 cars dyno tested and all did very well) on 243s, a g5x1 cam (228/232 585/575), 90mm throttle body, fast intake, katech dampener, c5r chain, ported melling high volume pump, OBX headers, corsa pacecar catback
it made 414/400 the first time, with 2 vacuum leaks on the bottom of the FAST intake that were my fault, and some pretty beat up plugs. so im guessing it was closer to 420/405, as i doubt the vacuum leaks changed it up all that much @ WOT.
so maybe you're a tad low? that 420/405 number was done in the winter, and taking that & dyno differences into account, we're probably pretty close.
if you have HPTuners, or if the tuner will, post your tune here.
it made 414/400 the first time, with 2 vacuum leaks on the bottom of the FAST intake that were my fault, and some pretty beat up plugs. so im guessing it was closer to 420/405, as i doubt the vacuum leaks changed it up all that much @ WOT.
so maybe you're a tad low? that 420/405 number was done in the winter, and taking that & dyno differences into account, we're probably pretty close.
if you have HPTuners, or if the tuner will, post your tune here.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Well, you should have used a 90mm TB..
Have the tuner check and see what your Injector Duty Cycle is under load. I would guess that they are on the high duty cycle side of operation and you may benifit a little with 36 lb/hr injectors. Not a big concern if your PE AFRs are not going lean under full power.
That being said,, any changes that you make between the TB and the headers, will require additional tuning to get the most HP and efficiency out of the changes. Especially if you mess with the MAF and TB size. When you change all that, your LTFTs will most likely go high and you will go RICH in PE Mode.
02 ZO6
I have Stainless Works 1 3/4 primary LT headers, High Flow CATs, 3" cat back system, VARARAM, a self ported Fast 90, Self ported ported 90mm TB, Patroit Performance 11.1 Stage 2 heads, a lot bigger cam (240/240, 610 @ 114+4 and Im making 450 RWHP.
Bill
Have the tuner check and see what your Injector Duty Cycle is under load. I would guess that they are on the high duty cycle side of operation and you may benifit a little with 36 lb/hr injectors. Not a big concern if your PE AFRs are not going lean under full power.
That being said,, any changes that you make between the TB and the headers, will require additional tuning to get the most HP and efficiency out of the changes. Especially if you mess with the MAF and TB size. When you change all that, your LTFTs will most likely go high and you will go RICH in PE Mode.
02 ZO6
I have Stainless Works 1 3/4 primary LT headers, High Flow CATs, 3" cat back system, VARARAM, a self ported Fast 90, Self ported ported 90mm TB, Patroit Performance 11.1 Stage 2 heads, a lot bigger cam (240/240, 610 @ 114+4 and Im making 450 RWHP.
Bill
Race Director
Joined: Jan 2008
Posts: 16,028
Likes: 170
From: oregon
I think that is pretty much right on for your mods and it being an auto. People telling you 450rwhp with those mods through an auto is pretty misleading. You would probably be in the 430 rwhp range with a stick. I would suggest upgrading to a 90mm TB. No point in having a fast 92 with a tiny stock 78mm TB. LS2 tb and adapters are cheap and very easy to install.
I'm not sure about the LPE headers but I'm guessing they're older and leave some room on the table for improvements. I would look into getting a set of super pro 1 3/4" LG's or 1-7/8" AR or Kooks headers.
As others mentioned the 3.73's make the car caster but on a dyno only situation they're robbing HP.
You could eventually have the heads fully CNC'd as well. Cam seems fine. I wouldn't be too worried. I bet on the strip if your car hooks you would run right along side if not beat a 450 rwhp stick car.
I'm not sure about the LPE headers but I'm guessing they're older and leave some room on the table for improvements. I would look into getting a set of super pro 1 3/4" LG's or 1-7/8" AR or Kooks headers.
As others mentioned the 3.73's make the car caster but on a dyno only situation they're robbing HP.
You could eventually have the heads fully CNC'd as well. Cam seems fine. I wouldn't be too worried. I bet on the strip if your car hooks you would run right along side if not beat a 450 rwhp stick car.
the header upgrade that is
anyone ask op what the outside air temp was? humidity ?
it's probably the worst time of year most places for making hp
dyno that car in jan and see what it puts down, you may have your 430-450hp
it's not uncommon for the same car to be 3 tenths apart in march vs august
Drifting
Joined: Sep 2009
Posts: 1,719
Likes: 4
From: cinnaminson n.j.
St. Jude Donor '14
the number didn't change, it's still 400
You are leaving a lot just with the heads alone, the 215's are a better head and made for that size bore and they come ported and polished ...
also bottlenecking:
-Stock MAF (screenless)
-Stock Ls1 throttle body (Ported & Polished)
-Throttle body Spacer
-Fast ls1 TB adapter
nice build by the way
You are leaving a lot just with the heads alone, the 215's are a better head and made for that size bore and they come ported and polished ...
also bottlenecking:
-Stock MAF (screenless)
-Stock Ls1 throttle body (Ported & Polished)
-Throttle body Spacer
-Fast ls1 TB adapter
nice build by the way
The injectors are probably maxed out as well. You should be running at least 36lb. or 42lb.. The car will never accelerate from a stop like it did with the stock cam without a different converter. The stock cam will make a lot more torque from 800-2000 rpm than the cam your using now. Take car of the things mentioned above and get a good converter (3000-3600 stall) in there and the car will launch hard and keep pulling strong to 6500+.