My post did come across as I was disagreeing with you. When I mentioned your name It was in a good way, I was taking your side as to why you were looking at a probable 11-13 minutes and Mervyn was not even close..I see runtime arguements all day long when one guy has an 8 pound D8 and the other guy has a 7 pound XRAY and they argue that runtimes vary

Gotcha! Good deal. I was thinking we have never had an issue with one another and why would it start now after several years of being regular active users. No harm no foul, lets drive on with our mission. Hoorah!

On a better note, I sold 5 of these engines already and my shipment has not even arrived yet! Got some extra o-rings and a rod coming also. This engine will be killer for the price point

So now you want me to come back at you and tell you that I did not "forget" anything? I wouldn't even have said something, when we were talking about 1 or 2 minutes difference in runtime. And: since the major difference, his completely ported version vs. my stock testing enginge, has already been found, you can safely take your list and put it to good use in a book about runtimes in general.
Rest assured that I do not drive a 10 pound mud-loaded never maintained truggy with no bearings and 15 yrs old fuel. I think I wouldn't have been handed a new engine to test if my gear was not in top shape. With THE Car I actually drive one of the lightest cars with on of the most freely running drive trains, I guess? And I think I stated in my post that all the major circumstances that affect runtime were taken into account (tune, pipe, fuel, plug, track conditions) and I still could only race like 8:xx mins tops and therefore can never see a stock Arrow GTR in a 12-13 minutes stint in a race. But if you show me with your list how you can make this testing engine I have had run 12-13 minutes under race conditions, I will sure as hell buy all my future engines from you and happily pay the overseas shipping costs.

I know that there are people who manage to have a engine like the Plus 4,
which is perfectly capable of long stints, only run like 6:30 and complain about the bad milage in forums, but if I was one of them, I wouldn't have posted here, I would have bought an Arrow after Mark's post and posted in two weeks time because I only could get the sucker to run 5 minutes. In which case your list would be appropriate.

Nevermind. Christ I wasn't attacking anyone, just pointing out the reasons for the run time differences. Fuc$in children

I wasn't attacking you either, just pointing out that your list is very much appreciated and yet unneeded in this case, because we already found the probably biggest reason for the different runtime. And I closed with a big grinning smiley, dude - even someone who is obviously quickly on 240 should be able to tell that it was all in good blood. So let's keep it that way, daddy-o.

My bad, and my apologies. It sounds like you know your stuff so let's discuss some more a few of the things missing from my list.

What were track conditions like?
What plug were you using?
What were ambient temperatures and humidity?
3 or 4 shoe clutch? What springs?
Light medium or heavy flywheel?
What tires and rims and how heavy were they?
What fuel were you testing with?

This is all relevant to me as a dealer because as a racer a possible 10 minute engine is allot more valuable than an 8 minute engine. Especially here in AZ where most mains are 20 minutes. I would like to have a civil conversation about whether or not it's possible for this engine in stock form to go 10 minutes in AZ with the proper set-up

I love it when racers believe their engine will go 10+ minutes in the main and they run out of gas. Happens at just about every big race I attend and they're about to kill their pit man. You change 2 or 3 variables above and run time goes down significantly. I would tell folks this engine will do 10 minutes...if you can drive it smoothly. Anything else is just a false hope as many racers do not set up their vehicle and driving style for fuel economy.

+1

The first day of testing we have been on a loam track where it rained the night before and we had a good overcast and tons of traction during the am.
The second day we have been on a very dry natural soil track with near to none traction at all but a with a layout that forces one to heavily pull the trigger. So on both tracks I have been quite trigger happy to start with.

Plugs has been O.S. P4 on both days, humidity was quite high on the first day and almost absend on the second day. Clutch was a fresh Xray 3-shoe aluminum clutch on both days with a standard 808 flywheel. Tires and rims have been Proline Crime Fighter M3 with blue closed cell inserts on V2 rims on both days to keep the comparison alive. All test-drivers used the same fuel (www.gt-racing.de we used GT-R Offroad 25%), an AE3-based fuel and I tend to say the best money can buy in our region. It is a small company not aiming for most profit but to make a fuel containing the best ingredients they can buy and therefore have happy customers. I think that the fuel even gained some more runtime than what I would have gotten with some standard castor-oil fuel.

On both days I did not manage to enter the 9 minute time window. As for the location: Testing has been done in Bavaria, Germany. Maybe our altitude takes part in runtime differences. We have been taking the Arrows test quite seriously and watched out for comparable situations. The first test-driver, who is way more experienced than I am and not half as trigger-happy, also managed to run around 8:45 mins. Only the last test-driver who tested with a 6 mm venturi nearly hit the 10 minute marker. So maybe!, if you take EPA to 80%, lean it a bit more that you would with full throttle possible and get in a good flow with your American stlyed tracks, there might be a 10 minute stint planable.
The first test driver, who also reads here, said today, that in the US longer runtimes are mostly common due to your great track layouts which dont force you to abruptly break and accelerate again all the time. I personally can still not see 12-13 mins but maybe, if all plays out well, 10 minutes are doable on a regular basis.

Thanks mervyn

great post...thx! all the fine details such as clutch,driving style,weather, and track conditions. btw what pipe were you running?

thanks Mark

3 local AZ guys picked up their Arrow engines from me this week so in the next couple of weeks I should have some really good feedback about how it reacts and performs here in desert conditions. We are coming into summer months so that means 100 plus degrees and 0 humidity.

Ran an Arrow GTR 21 for the first time today in my 8T 2.0, and I have to say it's an impressive mill, good balance of top and bottom end for our UK tracks (wide open, very fast) and a very smooth power delivery. I've run Alpha Plus for the last year, with the S852 'Orange' motor in truggy. The Arrow has about the same top end, a little less bottom but is slightly smoother to drive I would say.

Ran five qualies and a thirty minute final, only motor issue was it going rich when she finally broke in mid-Q4, but that was an easy fix. Other than that no flame outs or other quirks, and pretty good fuel millage for a new motor - running the 9mm venturi I think I could have just got 10 minutes. I opted to play it safe and settle for 3rd in the A-main on 8 minutes stops. Next weekend is our first national, so I'll drop to the the 8mm (possibly 7mm) venturi and start pushing the millage a bit.

Mentioned it in an earlier post, should have recapped it in the detailed one, sorry: