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Help with disappointing dyno results

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Old 07-02-2018, 09:58 PM
  #21  
fast.asleep
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Originally Posted by 383vett View Post
What timing are you running?
4* advance
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Old 07-02-2018, 10:05 PM
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Don't feel so bad about 250rwhp which, through an A4, translates to ~300chp.
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Old 07-02-2018, 10:39 PM
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Originally Posted by fast.asleep View Post
I recently had the car tuned on a dyno prior to a blower but the dyno results were seriously disappointing. I can feel an improvement over stock but not ads much as I thought.

It only made 250 rear wheel hp!!!

The car starts hard (I expected this since we removed the 9th injector) and surges on cold start up but the surge goes away as it warms up.

My mods are:

Engine:
80000 km’s (aprox 50k miles)
Stock bottom end
AFR 180 eliminator heads
Comp 268 xfi hr13 ( duration @50 218/224)
High flow L98 base, ported SLP runners, ported plenum
Adjustable fuel pressure regulator

Exhaust:
Long tube headers
True dual exhaust
Magnaflow mufflers

Transmission:
700r4
2400 stall torque converter
Shift kit

Considering everything I’ve heard on the forums I think something is wrong. If anyone has any words of advice please chime in
Hi

How old is the fuel pump and fuel filter?
I would start looking at replacing the fuel filter, standard the fuel pressure should be 40psi.
The TPI loves 50 to 60 psi fuel pressure, not sure on the camshaft.
The car should run good, I got my 85 from std mid 14 sec quarters to 13.2 sec quarter mile with minor works using standard cam and heads. Went to the blower after that..
Cold air intake long tube headers a tune up, cut air filter lid and adjustable fuel pressure regulator..
That is with street tires, so you should be able to get into mid twelve second quarters with what you have.

Try to no go overboard with a hot cam with TPI runners, go to a mini ram or super ram setup.
The std TPI runs out of breath at low rpm, you want to have a torque monster to accelerate from the line.
From idle to mid 5k rpm, anything else you are sacrificing torque and off the line launch.
That first gear is great to give you a launch, with a blower its all about torque so very mild cam suits best.

With all my mods the car ran good, easy start hot or cold.
Look into new 30lb injectors, and standard fuel limiting removal.
Check with fuel injector connection (FIC), they can help sort out your C4 -- make her fly.
https://fuelinjectorconnection.com/
Cheers

Last edited by gerardvg; 07-02-2018 at 11:00 PM.
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Old 07-02-2018, 11:00 PM
  #24  
fast.asleep
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Originally Posted by gerardvg View Post
Hi

How old is the fuel pump and fuel filter?
I would start looking at replacing the fuel filter, standard the fuel pressure should be 40psi.
The TPI loves 50 to 60 psi fuel pressure, and long tube headers.
You must use long tube headers to wake the L98, not sure on the cam
Iím pretty sure the fuel pump is original. Iíve had the car since 1990 and it hasnít been replaced since then. The fuel filter is about 10 years old. The car has long tube headers
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Old 07-02-2018, 11:07 PM
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gerardvg
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Originally Posted by fast.asleep View Post


I’m pretty sure the fuel pump is original. I’ve had the car since 1990 and it hasn’t been replaced since then. The fuel filter is about 10 years old. The car has long tube headers
Hi
Yeah look at replacing the fuel pump fuel filter and 30lb injectors, the standard fuel injectors can struggle with higher fuel pressure.
plus look at the FIC fuel injector tests, how poorly some flow just dribble a best.

Last edited by gerardvg; 07-02-2018 at 11:08 PM.
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Old 07-03-2018, 08:36 AM
  #26  
856SPEED
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Originally Posted by fast.asleep View Post


if a cam, heads and longtubes gives me 50 hp, I canít see an intake giving me 40.



yup. That was the cam that was in it during the dyno tune
it will....itís holding you back ...like my Edelbrock hi flo base and runners did...mini ram picked up 40 rwhp before the tune...same heads and cam....been there done that.
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Old 07-03-2018, 09:35 AM
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New pump and injectors would not hurt anything. The a/f ratio looks reasonable but just the average of 1 bank so really don't know much beyond that. Ignition timing would be good to know if left stock or changed. Personally would have used more cylinder head and cam. over 30 year old injectors kind of silly to keep too.
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Old 07-03-2018, 10:46 AM
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Based on what youre saying, its only the injectors that seem like they could be going off if theres actually something 'wrong' with it at all. It may just be out of breath due to the intake.
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Old 07-03-2018, 11:52 AM
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Originally Posted by vader86 View Post
Based on what youre saying, its only the injectors that seem like they could be going off if theres actually something 'wrong' with it at all. It may just be out of breath due to the intake.
I agree. You can tell from the dyno itís running out of breath at 4500 where the torque is falling off and peaks out early and falls quickly. I canít see before 4,000 RPM , but my guess it is making over 300 foot pounds at the tire around 3,000 RPM or so. Thatís no way to make horse power. You want s flat torque curve across the board. But that is the TPI world.

Timing is another good point. My car likes a bunch of total timing at WOT at high RPM...makes the best power at 36 before TDC ....But that can be risky too depending on your thermostat and cooling system in general.
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Old 07-03-2018, 11:57 AM
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Ok thnx. Since a blower is in the future should I swap to a mini ram or put that money towards the bottom end?
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Old 07-03-2018, 12:37 PM
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Depends how much boost you want to feed it. I considered a blower at some point and would've had the engine built for that compression and a fair amount of boost, I wouldn't run much boost on the stock bottom end.
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Old 07-03-2018, 07:38 PM
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Originally Posted by 856SPEED View Post


.... I can’t see before 4,000 RPM , but my guess it is making over 300 foot pounds at the tire around 3,000 RPM or so.
Pretty close. 331 foot lbs at 3724 rpm. (Forgot to attach the first sheet) I may just try the mini ram after all. Do you know of any used ones?

Last edited by fast.asleep; 07-03-2018 at 07:38 PM.
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Old 07-04-2018, 07:40 AM
  #33  
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Originally Posted by fast.asleep View Post


Pretty close. 331 foot lbs at 3724 rpm. (Forgot to attach the first sheet) I may just try the mini ram after all. Do you know of any used ones?

There might be some out there on ebay or wherever. Or you can call TPIS and ask them if they have a deal they can work out for you. You need the fuel rail system they have as well. I originally did not believe the TPI intake system would be so restrictive when I did my build many moons ago. But I quickly found out why the mini ram was so expensive after looking at my dyno test and taking it to the street and track and going up the competition. It came out of the hole like a scared rabbit, but the party ended at about 60mph when I was looking at tail lights. The mini ram changed all of that (same cam and heads). Also, looking at your A/F ratio, there is no fuel delivery issues at all. Your A/F ratios are safe at less than 13:1 at WOT. That doesn't tell you it is starved for fuel at all. In fact if they leaned it out to about 13.2:1 at WOT or so, it would put down a little more power and I don't have a clue what kind of timing you are running, another important factor (at WOT). SBC like a lot of timing at WOT. The LS engines actually do not need as much timing due to the efficiencies of the cylinder heads.

Having said all of that, I would not be too upset by your numbers. You have some torque at the tire off the stop light and overall it should be a fun car to drive.

Last edited by 856SPEED; 07-04-2018 at 07:47 AM.
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Old 07-05-2018, 11:16 AM
  #34  
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I would want to see the knock counts if any at WOT as timing might be leaving something on the table. If none I would be tempted to move the timing up until on or two and if a bunch take some out as ECU might be pulling too much out.
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Old 07-06-2018, 09:25 AM
  #35  
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Originally Posted by fast.asleep View Post
Compression? I want to say stock. As for peak hp and torque:







Testing a TPI all over 4600 RPMs is laughable. What they other guys are telling you about the intake making HP is simple. HP is the ability to make Toque at high RPMs. Your Heads/Cam are designed to make power Higher than the SLP Runners. It's not matched well.

As with anything mods, Data log and ensure health and function before getting too upset. Also, if your Cam... and I didn't look for any details here, is designed for a blower, don't expect it to add a lot NA. It will come alive under boost.

If you want HP a mini Ram or similar will be needed.

Last edited by KyleF; 07-09-2018 at 01:47 PM.
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Old 07-06-2018, 10:21 AM
  #36  
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Originally Posted by KyleF View Post
Torque is the ability to make HP at high RPMs. .
Backwards.

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Old 07-06-2018, 11:11 AM
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ddahlgren
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hp=(torque X RPM)/5252
so hp is the rte you can generate torque.
No torque no hp.
Torque generally falls off 15% between peak torque and peak HP so bigger the torque number and the longer you can hang on to it the more HP.
This engine is only making 7 more HP between peak torque and peak HP it is basically a 245 HP engine and probably only has 245 worth of airflow.
The only chance for a low buck help might be 1.6 or 1.65 rockers to put some area under the curve for more air flow.
With the typical loss of 15 to 20% for rolling resistance trans u-joints tc. On it's best day this is a 380 to 395 ft.lbs and 280 to 300 HP at the flywheel.
This is about what you would expect from the intake and heads.
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Old 07-06-2018, 05:21 PM
  #38  
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Originally Posted by ddahlgren View Post
With the typical loss of 15 to 20% for rolling resistance trans u-joints tc.
15-20% is very generous. I see numbers closer to 10% on Dynojets.

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Old 07-06-2018, 07:12 PM
  #39  
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fair enough. Most of the stuff I have run on a dynojet are bikes and they get sensitive in how tight you strap them down or tire inflation. Would not have believed it if did not see it more than once on turbo busa's. Usually around peak torque when needs to tied down tighter to get a better bite on the roller. I have run hundreds if not thousands of engines though few on chassis dyno's. Hooking the car or bike up is generally more trouble than what is learned. They do in my experience work well for finding drive response and an ocassional miss that is hard to catch in a data stream though.

Last edited by ddahlgren; 07-06-2018 at 07:12 PM.
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Old 07-06-2018, 09:05 PM
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Originally Posted by Tom400CFI View Post
15-20% is very generous. I see numbers closer to 10% on Dynojets.
recent dyno on ls1 = 593 engine hp. Same engine in car made 492 whp, that was a manual tko 600 trans and ford 9 inch rear on a mustang dyno. 17% drive train loss. I do agree with you that the factory numbers read higher, more like 10% on a manual and 15% auto.
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