Competition Doing some testing

[Jim Fulmer]

The outcome is really weird to me.



Twins SPS 66/Big Brother- Tweaked 215 pump, stock DV's, lines and 370's 75 psi of boost... . EGT's 1550-1600.



Single SPS 66 with the same setup at 50 psi..... EGT's call it 1650.



Both are without any water.



The Twins power is better but not a huge amount.



Drive pressure checks are next.



Jim

 

[Bandit1]

so you going to keep the single jim? one thing comes to mind while reading your post. you can only move so much air through the head, it is the bottleneck of this motor. u may be on to something. how does the lag compare between the 2 setups? u experienced any surge yet? josh

 

[Jim Fulmer]

Lag is either the same or a little better but no worse. It does not have quite the hit of the Twins.



The Twins will definitely take more stuff and stick it through the motor.



If I run the single and EDM injectors with the pump full tilt and both stages of water it will "blow the fire out" or bang a little till high RPM or EGT, but with Twins it will run clean. Turn the water off running the single it's fine but WOW the smoke is huge.



Yesterday running the 370's and both stages of water it would do it a little till I put a 50/50 mix in..... it likes that! Now drop to one stage of water it's fine even with washer fluid.



I've just about got the R&D done for this combo so something new needs to happen.



I think I'll stay with the single but get a new housing ported to get more out of the motor.



Look back at the two different boost levels (50 psi Single) (75 psi Twins) both air temps are about the same 150 degree range.



No surge yet... . not even a tiny bit, it loves to run or cruise!



Jim

 

[RacinDuallie]

Jim any porting done on that head?

 

[Jim Fulmer]

Yep, flows 214 intake, 198 exhaust at . 550 lift..... it's actually done right after . 450.



Jim

 

[thekidfan]

Lag is either the same or a little better but no worse.



Jim

Jim, is that suprising to you? I would've thought it would be concideribly faster as a single

About where do you think you are HP wise on #2?



Off Topic: when you coming into TAFB again?

 

[Jim Fulmer]

Jim, is that suprising to you? I would've thought it would be concideribly faster as a single

About where do you think you are HP wise on #2?



Off Topic: when you coming into TAFB again?

I guess it's a little faster initially and of course it's faster on the smack, not much different than others have posted. I'm trying to tune it to drive pressure now as I finally go it hooked up today. It's higher than I wanted but I knew I was getting greedy as I tighten the gate up 4 full turns from where I. I initially set it and gain no boost.



Travis... . I deploy week after next again and should go there first... . I think, it's a different month. When I'm there it's very busy and flying day, day, night, night, day... . in other words it stupid schedule. PM me anyway if you are around.



Let's say about 650 area on power..... that is a guess! It may be higher but I won't guess that way.



Another thing I did was put the air temp probe in the inlet after the filter, there a big difference in 130 degree air vise 80... . big difference.



Jim

 

[Jim Fulmer]

Since returning home I've fixed the fuel tank gauge, exhaust and hooked up the drive pressure gauge. Ah the simplicity of a single and not having to work on it all the time.



Jim

 

[Jim Fulmer]

Coming close to the end of testing as it sits. Boost/Drive pressures are 1 to 1 now, they were just a tad off till I backed off the gate 3 full turns. I might try 2 more just to see what happens.



I hooked my old big turbo gauge up so now I have full time drive check. Since putting it back together as a single I've put say 700-800 miles on it and have done nothing except have fun. I have not tighten one clamp, fixed one leak or tweaked one thing except shorten the 4" down pipe to fix a clearance issue with the 5" exhaust.



So the single change over was a good one as I see it, but it could stand for just a little more power on special occasions. As for daily driving it just fine, ok I might try a set of Dragon fly's (Stage 2 370's) but no bigger as I already have a big set of injectors.



Anyone want me to test anything else other than injector swaps on the dyno?



Jim

 

[JGheen]

Anyone want me to test anything else other than injector swaps on the dyno?



Jim

I would be interested in more info on how you got your boost/drive pressures 1 to 1. I have serious surging issues with my set-up in the higher gears and I think I could get much more "cleaner" power out of my engine if I tinkered with it more like your doing with yours. Where did you get a drive pressure gauge at and where did you take the reading from?



Joe

 

[Jim Fulmer]

Joe, I have two ports in the manifold and did when it was in the Twin set up. Now with the manifold flipped over the ports are on the bottom for the drive check and EGT probe. The drive pressure comes from the front three cylinders and the EGT comes from the aft three cylinders.



I went to the parts store and they had a gauge kit with 6 feet of 1/8th brass line, so I bought it and hooked it into my existing gauge like that runs into the cab and is mounted on the column.



On the drive pressure checks I had the turbo making around 45 psi so I put three turns tighter in the wastegate and the boost didn't change so now I have that taken out.



The other day (I'm talking a week) I though it might surge as the converter locked early but it just wouldn't do it. I run around town with the converter unlocked most of the time as I have a TPS disease in my truck so I control it manually.



Jim

 

[Jim Fulmer]

I might, just might be able to get on the dyno this weekend. It always helps when you have someone that needs something done and he owns a dynojet.



Jim

 

[Jim Fulmer]

I got to make a few pulls today but too short for an injector swap mid stream. Results were 611hp on #2 only with pump issues (self induced from Sat night) several issues are noted and will be checked out. Not too bad for a stock pump and 370's and only running 40 psi of boost.



Jim

 

[Forrest Nearing]

Jim, I know you love that sps66 (got one sitting at Wes' shop waiting for me... giving serious consideration to swapping it on in place of my twins (I miss the "smack" )



but you gotta admit, that head and cam have got to be helping to push the surge line to the left, no?



oh, and I think you and I both know where a little more power for special occasions can come from :-laf :-laf :-laf sorry, that stuff always makes me giggle

 

[Jim Fulmer]

I actually almost made it surge the other day. I was taking off with the converter switch locked so when it picked up second it locked the converter then picked up third right after that, both were at real light throttle and low speed..... like maybe 25-30. One thing I have never liked is not being able to hold second, you can hold it to 2220 accelerating then it picks up third.



You may be very right on that surge issue. Still don't like the cam and it going to get changed... . again, just not enough bottom end, but it flys in the higher RPM.



N2O would be scary on this truck, imagine Jet Pilots setup on my truck... ... . that would break so stuff.



Pulled the pump yesterday and set it back like it was but didn't finish the install, had to get things ready to leave. Hopefully it will fix the issue that I had as I lost 5-6 psi of boost with no leaks, then I'll have to tackle the water issue.



Jim

 

[Forrest Nearing]

heck, just the head porting is probably enough to chase away any surge... it's really just the 12v trucks that report surge due to such low cylinder head flow...



nobody said you had to hit the thing w/ 5lbs of juice every time you squeeze it, but a little to take up the slack from the missing big brother would be fun, no?



I've got just the cure for that 2-3 shift problem. PM on the way