DYNO TESTS WITH AMERICAN SPEED LS7 700 HP

[skidiiii]

Looking for some real world results on what other Ultima owners have actually been able to produce on the dyno with 700 hp@6600 rpm, 625 ft. lbs. torque @4500 rpm, 11.5 comp, dry sump, all aluminum, fuel injected. Emission legal in all 50 U.S. states. Turnkey built by Gail at American Speed. Results with Ultima exhaust system and custom exhaust system? Expected average loss through trans-axle G50/02 or 03 any input would be greatly appreciated!

[mt308]

I know this doesn't answer your question but the dyno I had supplied with my engine (not in the car/at the wheels) was 704hp max and 645ft lbs max.

[skidiiii]

Yes that is what they claim the engine will produce at the crank. I am looking for anyone who has actually run a dyno test after it was installed. It would be great if anyone can post their actual results sheet. Big investment for 700 claimed hp

[Storer]

Not a 700hp American Speed engine but my standard crate LS7 has dyno tested in the UK at 577hp with a bespoke exhaust and a bit of GM ECU tweaking. GM state it is 505hp straight from the crate, so a reasonable gain for very little cost.

The extra 123hp may prove to be more difficult to achieve than people think. Many US built SBC engines proved to have a lower power output than stated on the build dyno when tested in the UK. A bare engine will undoubtedly produce more than one with all ancillaries.

The important bit is how driveable the car is. You need to be able to floor the throttle in second gear (with sticky tyres and a dry, warm road) without spinning the wheels otherwise what is the point of the extra power. My car will do 90mph in second and you can pull away from standstill in second too. It will still blow pretty much anything else off the road.

Don't get too hung up with wanting a big number engine unless your willy is very, very small.


Paul

[skidiiii]

Wow, thanks Paul. So to understand correctly. You have a GM crate engine with a bespoke exhaust in an Ultima and are able to produce 577 hp at the wheels with a GM ECU? If so you are the man!!! Do you have a dyno sheet? Curious how it was run and what RPM range you hit. Thanks for the reply

[Storer]

Not at the wheels. At the engine.



The figure at the wheels from a 700hp engine is likely to be near 577hp after transmission losses.

Too much power can lead to a car that is no fun to drive.

Having said that, I might put a cam in mine to get about 650hp in a year or so when I have finished my current project!!!!


Paul

[JoulesCanAm]

mt308 said:

I know this doesn't answer your question but the dyno I had supplied with my engine (not in the car/at the wheels) was 704hp max and 645ft lbs max.

I believe the dyno sheets that American Speed supply are a desktop dyno, not physical results. My AS engine was down 60HP when first installed. On a chassis dyno you have to make some assumptions for drive train loss, we also had to compensate for altitude as I'm at 4,500 ft.

Julian

Edited by JoulesCanAm on Sunday 19th January 02:50

[mt308]

JoulesCanAm said:

mt308 said:

I know this doesn't answer your question but the dyno I had supplied with my engine (not in the car/at the wheels) was 704hp max and 645ft lbs max.

I believe the dyno sheets that American Speed supply are a desktop dyno, not physical results. My AS engine was down 60HP when first installed. On a chassis dyno you have to make some assumptions for drive train loss, we also had to compensate for altitude as I'm at 4,500 ft.

Julian

Edited by JoulesCanAm on Sunday 19th January 02:50

Sorry if this is a silly question but what do you mean by a desktop dyno?

Mark

[karl c]

mt308 said:

JoulesCanAm said:

mt308 said:

I know this doesn't answer your question but the dyno I had supplied with my engine (not in the car/at the wheels) was 704hp max and 645ft lbs max.

I believe the dyno sheets that American Speed supply are a desktop dyno, not physical results. My AS engine was down 60HP when first installed. On a chassis dyno you have to make some assumptions for drive train loss, we also had to compensate for altitude as I'm at 4,500 ft.

Julian

Edited by JoulesCanAm on Sunday 19th January 02:50

Sorry if this is a silly question but what do you mean by a desktop dyno?

Mark

Mark I would presume that Julian means bench tested as apposed to a rolling road test with the engine installed in the car and the BHP taken at the wheels.

Karl.

[pilbeam_mp62]

karl c said:

mt308 said:

JoulesCanAm said:

mt308 said:

I know this doesn't answer your question but the dyno I had supplied with my engine (not in the car/at the wheels) was 704hp max and 645ft lbs max.

I believe the dyno sheets that American Speed supply are a desktop dyno, not physical results. My AS engine was down 60HP when first installed. On a chassis dyno you have to make some assumptions for drive train loss, we also had to compensate for altitude as I'm at 4,500 ft.

Julian

Edited by JoulesCanAm on Sunday 19th January 02:50

Sorry if this is a silly question but what do you mean by a desktop dyno?

Mark

Mark I would presume that Julian means bench tested as apposed to a rolling road test with the engine installed in the car and the BHP taken at the wheels.

Karl.

No - reading the tone of his post, what I think he is implying is that AS just make up the figures using a lot of assumptions and a spreadsheet, and don't actually RUN the engine before dispatch - I don't think this is the case at all.

Here is the dynosheet from the engine that I bought from AS when I built my car....

Edited by pilbeam_mp62 on Sunday 19th January 13:40

[mt308]

pilbeam_mp62 said:

No - reading the tone of his post, what I think he is implying is that AS just make up the figures using a lot of assumptions and a spreadsheet, and don't actually RUN the engine before dispatch - I don't think this is the case at all.

Here is the dynosheet from the engine that I bought from AS when I built my car....

Edited by pilbeam_mp62 on Sunday 19th January 13:40

I wasn't sure if that's what was meant. My AS engine (the one being referred to here - 700hp LS7) came with a similar sheet (exactly the same format). The engine itself had been run to produce the sheet. The figures are the figures I quoted above.

I think all manufacturers quote the engine at the flywheel?

If it helps you decide, it is an incredibly quick car, and is pretty easy to drive around town without any spluttering. I think this is where big hp on SBC engines suffer - there are not great at sitting in traffic.

I can also say I have had no cooling issues at all. When just registered I sat in a 4 hour traffic jam on the way back from Goodwood in the heat. Whilst the cooling fan and air con were both on permanently for all 4 hours, the temperature of the engine never went about 90 per the gauge and the interior stayed fairly cool. The engine also never missed a beat.

[skidiiii]

JoulesCanAm said:

I believe the dyno sheets that American Speed supply are a desktop dyno, not physical results. My AS engine was down 60HP when first installed. On a chassis dyno you have to make some assumptions for drive train loss, we also had to compensate for altitude as I'm at 4,500 ft.

Julian

Edited by JoulesCanAm on Sunday 19th January 02:50

Thanks for the reply Julian, Was the 60 hp loss at the crank again with Ultima exhaust system or is this what dropped at the wheels when installed. Trying to put my head around what the expected drive train loss and Ultima exhaust will degrade the crank HP to.

[skidiiii]

mt308 said:

I wasn't sure if that's what was meant. My AS engine (the one being referred to here - 700hp LS7) came with a similar sheet (exactly the same format). The engine itself had been run to produce the sheet. The figures are the figures I quoted above.

I think all manufacturers quote the engine at the flywheel?

If it helps you decide, it is an incredibly quick car, and is pretty easy to drive around town without any spluttering. I think this is where big hp on SBC engines suffer - there are not great at sitting in traffic.

I can also say I have had no cooling issues at all. When just registered I sat in a 4 hour traffic jam on the way back from Goodwood in the heat. Whilst the cooling fan and air con were both on permanently for all 4 hours, the temperature of the engine never went about 90 per the gauge and the interior stayed fairly cool. The engine also never missed a beat.

Did you ever Dyno your car at the wheels to see what your 704hp AS engine is producing after drive train loss? This is the root of the question I have posted.

[mt308]

skidiiii said:

mt308 said:

I wasn't sure if that's what was meant. My AS engine (the one being referred to here - 700hp LS7) came with a similar sheet (exactly the same format). The engine itself had been run to produce the sheet. The figures are the figures I quoted above.

I think all manufacturers quote the engine at the flywheel?

If it helps you decide, it is an incredibly quick car, and is pretty easy to drive around town without any spluttering. I think this is where big hp on SBC engines suffer - there are not great at sitting in traffic.

I can also say I have had no cooling issues at all. When just registered I sat in a 4 hour traffic jam on the way back from Goodwood in the heat. Whilst the cooling fan and air con were both on permanently for all 4 hours, the temperature of the engine never went about 90 per the gauge and the interior stayed fairly cool. The engine also never missed a beat.

Did you ever Dyno your car at the wheels to see what your 704hp AS engine is producing after drive train loss? This is the root of the question I have posted.

No I haven't done that. Would be interesting. Will look into it.

Mark

[Ult-Jim]

Storer said:

Not a 700hp American Speed engine but my standard crate LS7 has dyno tested in the UK at 577hp with a bespoke exhaust and a bit of GM ECU tweaking. GM state it is 505hp straight from the crate, so a reasonable gain for very little cost.

The extra 123hp may prove to be more difficult to achieve than people think. Many US built SBC engines proved to have a lower power output than stated on the build dyno when tested in the UK. A bare engine will undoubtedly produce more than one with all ancillaries.

The important bit is how driveable the car is. You need to be able to floor the throttle in second gear (with sticky tyres and a dry, warm road) without spinning the wheels otherwise what is the point of the extra power. My car will do 90mph in second and you can pull away from standstill in second too. It will still blow pretty much anything else off the road.

Don't get too hung up with wanting a big number engine unless your willy is very, very small.


Paul

Just about sums it up. Until that day you have some free cash and want to keep up with the Jones's and start experimenting with more power.

[skidiiii]

Ult-Jim said:

Just about sums it up. Until that day you have some free cash and want to keep up with the Jones's and start experimenting with more power.

Or to see if what you are paying for is actually what you are getting???

[deadscoob]

I think you have a better chance of getting near the quoted numbers once it's in the car if you have a good set of headers made.

[skidiiii]

So how would the Ultima exhaust stack up against a custom set? Would there potentially be a huge difference one way or the other?

[Steve_D]

I would expect the engine to produce less power on the Factory exhaust system compared to the system used on an engine dyno. The dyno system is just there to get rid of the fumes. The Factory system has to achieve 99dBA so will be way more restrictive.
On that basis there is no way you can compare the figure produced by AS with the figures achieved on a rolling road.

Steve

[skidiiii]

Steve_D said:

I would expect the engine to produce less power on the Factory exhaust system compared to the system used on an engine dyno. The dyno system is just there to get rid of the fumes. The Factory system has to achieve 99dBA so will be way more restrictive.
On that basis there is no way you can compare the figure produced by AS with the figures achieved on a rolling road.

Steve

That makes sense. So I presume that AS Ultima 700 HP LS7 must be bench tested with virtually no exhaust to achieve the 700 hp figures when in fact if sold as Ultima engine should really be tested with a more restrictive type or "factory exhaust" to have true real HP and torque numbers. Any ideas on loss of HP loss with factory vs custom there must be other builders who have tested different types??