Dyno results -- a 2.8 built by John Gregory
 

These are the dyno results for a 2.8 built by my 72-year-old mechanic, John Gregory; I was under the mistaken impression that this engine was a 3.0 liter.

These are the specs for this engine:

Compression ratio: <b>11.8:1</b>
Crankcase: <b>reconditioned 7R</b>
Ignition: <b>Single plug</b>
Cams: <b>GE-60</b>
Exhaust system: <b>SSIs with twin outlet muffler</b>

<img SRC="http://www.holscope.com/dyno_results_jb2.8.jpg" height=554 width=736>


Matt Holcomb
MFIWDP
<b>PRVC</b>
<b>BOHICA</b>
1974 911 Carrera 2.7 RoW<a href="http://www.holscope.com/74Carrera2.7" TARGET="_blank"></a>
1975 Mercedes-Benz 280SE
<a href="http://www.holscope.com/74Carrera2.7" TARGET="_blank">Dedicated Homepage</a>
<a href="http://www.holscope.com/74Carrera2.7/rebuild" TARGET="_blank">Engine Rebuild Homepage</a>
<a href="http://www.cheaterswayside.com/911/gallery.asp?sort=0&userid=127" TARGET="_blank">Porsche Owners Gallery Profile</a>
<a href="http://www.pelicanparts.com/cgi-bin/pmpre/pm.cgi?action=display&login=Matt_Holcomb" TARGET="_blank">Pelican Gallery Profile</a>

two questions -

what's that in HP?

and

does it run on pump gas?


sounds cool!

The graphs look smooth and impressive...... no ignition worries there.... Ill just have to spend some time converting it to HP and pound /feet of torque


The graphs are relatively uniform and smooth........ that is quite important

Bill,

<b>168 kW</b> is <b>225 bhp</b>. Remember, this is at the wheels!

As for the type of fuel this engine is running on, yes, it's 98 octane pump gas.


Matt Holcomb
MFIWDP
<b>PRVC</b>
<b>BOHICA</b>
1974 911 Carrera 2.7 RoW<a href="http://www.holscope.com/74Carrera2.7" TARGET="_blank"></a>
1975 Mercedes-Benz 280SE
<a href="http://www.holscope.com/74Carrera2.7" TARGET="_blank">Dedicated Homepage</a>
<a href="http://www.holscope.com/74Carrera2.7/rebuild" TARGET="_blank">Engine Rebuild Homepage</a>
<a href="http://www.cheaterswayside.com/911/gallery.asp?sort=0&userid=127" TARGET="_blank">Porsche Owners Gallery Profile</a>
<a href="http://www.pelicanparts.com/cgi-bin/pmpre/pm.cgi?action=display&login=Matt_Holcomb" TARGET="_blank">Pelican Gallery Profile</a>

Compression nearly 12 to one? It's not going to run on USA pump gas. But maybe they still use lead down under? I'm roughly guessing 110 octane needed with this engine...when pump gas is 92 here?

maybe someone here could help me with my new car and fuel/detonation concerns:
2.7 twin plugged with 10:1 compression (I still don't know what cam is used - if that is relevant?)
currently running on 93 octane US pump gas.
rgds Ben
any guesses to the power output? (weber carbs)

11.8:1 with single plug? THat must be some Fuel!

Pump gas in CA is 91
 

Can octane boost help someone like Twin Plugged Targa? Is octane boost recommended, or is twin-plugging the only way to deal with compression above 9.5 or 9.8?

Thanks.

That's impressive stuff! 225bhp @ the wheels!

MFI is John's preffered induction/fuel system, isn't it, Matt?

Hey! Congratulations Matt. 225 RWHP from a NA 2.8 is a damn good achievement!!!

SmileWavy

I know you've been very good about respecting JG's secrets, but you have to share some with us!!!

I think letting a couple slide and informing some of us Yanks won't take away from his business!!

I think once secret is out that he using insanely high CR's...and I am sure you've got a pretty racey cam on it.

how did you get that CR by the way...is it custom JE Pistons...or all Mahle parts???

anyways...sounds like a hot motor...perfect for my targa!!!

MJ

I got the same for the hp conversion:
168.2 KW = 225.56Hp

Assuming a loss of 13% for the tranny, that gives 260Hp at the crank. Thats 92Hp per litre...

For the torque conversion I'm getting:
733.1 Nm = 540.71 ft*lbs
Something must be wrong....

Wow Matt - you weren't kidding - that's pretty damn good!!!!

Puts your own engine in perspective too - that is 2808cc (if my maths is good) and yours is 2687cc, so yours would be 4.4% lower, less whatever you lose because of a few points compression...

We do ok in New Zealand - I got 245rwhp from 3186cc, but I only have S cams and 10.3:1 c/r.... (ok so twin plug and EFI is cheating back the other way).

Pump gas - it is 98 RON (same stuff in Aussie and NZ). I think it equates to 94 (RON + MON)/2

Cam

Paul,

Ideally, you'd want to run this engine on 100-octane fuel, but the 98-octane stuff is fine.

If you're interested, this is the 98-octane fuel I'm referring to:

http://www.shell.com.au/optimax


dd74,

Twin Plugged Targa's engine shouldn't need a high octane (98+) fuel.


Adam,

Well, he acknowledges the advantages of EFI systems like Wolf3D and MoTec, but he's a bit of a luddite, so he's really only comfortable with carbs, MFI, and CIS.


Merv,

It's not bad, is it? :)


82SC,

Unfortunately, I'm not privy to all of John's secrets. I asked him about the heads for this 2.8 yesterday, but he smiled and just waved his hand.

As far as I know, the pistons in this engine are Mahle; this engine cost US $20K to build.


Tbitz,

Is it 13% or 30%?


Cam,

Not to sound patronising, but your mechanic should be very proud of his achievement. :)


Matt Holcomb
MFIWDP
<b>PRVC</b>
<b>BOHICA</b>
1974 911 Carrera 2.7 RoW<a href="http://www.holscope.com/74Carrera2.7" TARGET="_blank"></a>
1975 Mercedes-Benz 280SE
<a href="http://www.holscope.com/74Carrera2.7" TARGET="_blank">Dedicated Homepage</a>
<a href="http://www.holscope.com/74Carrera2.7/rebuild" TARGET="_blank">Engine Rebuild Homepage</a>
<a href="http://www.cheaterswayside.com/911/gallery.asp?sort=0&userid=127" TARGET="_blank">Porsche Owners Gallery Profile</a>
<a href="http://www.pelicanparts.com/cgi-bin/pmpre/pm.cgi?action=display&login=Matt_Holcomb" TARGET="_blank">Pelican Gallery Profile</a>

Matt - he IS pleased! And so am I :D :D :D

Dyno losses I have seen and believe are about 9% (lowest I've seen - my dyno guy) to 15%. I wouldn't believe much over 15%.

See:

- http://forums.pelicanparts.com/porsche-911-technical-forum/82514-tranmission-correction-factor-dyno-readings.html?highlight=dyno
- http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic&f=1&t=004561&p=
- http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=11&t=000291

Plus I asked Bruce Anderson and he said 11-12%.

Haha - guess what my all-consuming area of interest is at the moment...

So, let me get this straight...

There is a secret to preventing detonation by doing something to the pistons? Does anyone know how this might be achieved?

I would think this to be pretty valuable information to anyone wanting to build a quick n/a car, provided they had decent fuel as it is..

Wow, $20K US. That is some serious cash. I know I plan on 'creating' a good club car, just don't scare me!

Anthony.

Geez, only just noticed the US$20k!

I cannot disclose what mine cost me, but it was less than that...

Geez, I just went and checked (I have a big spreadsheet). I can't believe what I did spend. I think I better burn the evidence before I get married (next year).

For $20k you would have thought it would have twin plugs.:rolleyes:

98 RON is about the same as what would be 93 CLC here in the states. The highest pump gas here I usually see is 91 CLC. Occasionally 92 CLC.

I did some checking on the web regarding octain and found this classic article on gasoline which will tell you all that you want to know (and quite a bit more) about octain, formulations, etc.

I found the following information for comparison on Steve Weiners Rennsport site as well as on the respective oil company sites.

Note: RON affects low and medium speed knock and run-on. MON affects high RPM and high load performance.

Gas.....................RON.....MON.....(R+M)/2
Shell Optimax.......98.......NA........NA
Sunoco Ultra 94....NA......NA.........94
Most other Prem...NA......NA.........93

Race Fuels
Trick Unleaded........96......104......100
Sunoco GT4.............NA......NA.......104
Unocal 76...............108......95.2.....100.2.

Tbitz;
I think the issue with the torque number is that it is based on a rear wheel measurement. So we would need to back out the mechanical advantage provided by the gear box. Apparently this was done with the HP calculation. Also it looks like you did the conversion for SAE HP. Porsches are traditionally quoted in DIN (metric) HP which is a little more conservative. I show this engine pulling 251 metric HP.

Matt: It looks like the run was in 4th gear, what sort of 4th gear ratio are you running? Also, what's the bore and stroke for your engine?

It appears that the GE60 does create a similar rev range as an early "S" cam, and is in fact a little bit milder since it doesn't seem to pull 7000 RPM. When I run some BMEP numbers for this dyno pull, it suggests that the GE60 cam does make a significant increase in power. Specifically the BMEP at peak torque goes from about 177 lbs/sq-in at 5000 RPM for a 2.7 RS up to 206 lbs/sq-in at 5500 RPM for Matt's car with a GE-60 cam (and a lot more CR!) It's hard to say for sure since being up over 200 lbs/sq-in puts this engine in the same category as a recent Honda F3 motor as well as a Vauxhall Super Touring motor, both of which have 4 valve heads, CR's and fully mapped engine management systems.

Hmmmmmmmmm:rolleyes: