JB Racing Cylinders

Andy@Altitude · 07-15-2019, 07:21 AM

Has anyone had any experience using JB Racing steel lined cylinders for air cooled 911?

MBruns · 07-16-2019, 02:38 AM

Andy, I have used them for years on many builds, what would you like to know
Mike Bruns

Andy@Altitude · 07-16-2019, 07:14 AM

Mike,
I run a turbo 3.5l (100mm bore) road/track car. I live in the near in mountains above Denver so drive between 7K and 8K feet of altitude so heat is a constant problem. I only ever run at <1bar boost. 8:1CR and 91 octane. I also just added water/meth injection at the intercooler outlet to help with heat.

I have had terrible problems with Nickies going oval with the smallest exposure to heat. Most recently I got to 400degF CHT for maybe 30 seconds and it was all over, huge oval at the top to two cylinders, must be replaced! Subsequent check of my FI's showed at partial clog on the two hot cylinders so about 10- 15% below the nominal flowrate of the other cylinders. My AFR average (at the inlet to the turbo) was about 12.5 so these two cylinders did get hot but for a very short period of time. This was on a new build, total 15 miles of VERY careful driving, no boost, even my grandmother would comment how slow I was driving.

So now I have two cylinders that are ruined after 15 miles. I am not sure what alloy Nickies use or how they are heat treated or what they do (if anything) to temperature stabilize the post machined cylinders. This is their secret sauce so I am not getting any answers. Machining from billet is great but when this much material is removed in the process of boring there are alot of residual stresses left behind. Either way I find the idea of a high strength ductile steel sleeve (which alloy 4130-4140 4340?) pressed or temperature shrunk into machined alum fins very appealing assuming much higher strength and temperature stability.

I already have replacement (100mm 8:1 3.3l) JE pistons. My questions are around how to size the cylinders for JE pistons that are designed for nickies (just a slight increase in clearance given lower thermal expansion of the steel?) and what affect with the steel sleeve vs. all machined aluminum have of the ability of the cylinders to get rid of heat?
Andy

MBruns · 07-16-2019, 07:44 AM

Andy, most all of your concerns are why we developed the iron liner cyls. We wanted control over bore size, bore stability, and the ease of freshening up the bore and ordering a new piston a few thou. larger when freshening up. We would usually look for a ring package that had plenty of options in the bore range we wanted to run and then choose the bore size and order pistons, vs. here's your bore size and hope you can find the ring style you want. Have you spoken to Jim Higgs at JB ? he will be glad to chat with you and help. I worked for him 12 years in the engine dept. and one of the projects and developments were these cylinders, we currently run these on our N/A 3.8 race car and have over 200 race hours on them over the years. I think the perfect cylinder would be these with a plating, but then you would loose the ease of honing to resize as easily.
Hope this helps, Mike Bruns

JB Racing 352-343-8900
Florida

Andy@Altitude · 07-16-2019, 07:15 PM

Mike,
I talked with Jim today. Very knowledgeable, no BS, a pleasure to talk with. Apparently there has been a cooperative conversation between J&B and LN Engineering over the years and most often between them it has been recognized in the larger bore turbo applications steel lined vs. machined billet aluminum is recognized as the way to go. I wish LN could be a bit more up front about this with me before I went through 2 sets of cylinders. However, for us tuners, this is the risk we all take, and love it!

The only other wrinkle is I had already ordered new J&E pistons but apparently the standard JE's are designed of aluminum cylinders and you need to have a different wall clearance and especially a different skirt design when running pistons in a steel sleeve. So back go those pistons to be replaced with a custom set of JE's specified by JB/Jim. So the entire kit of cylinders and custom pistons wlll run me about $5,000. We will not Nikasil plate the cylinders as is a more robust design in the short to mid term but may have a somewhat shorter life beyond 100k miles. Jim did not discuss what steel alloy they use for the liners but guessing they are not cast iron and would have a much longer life than cast iron. I'll be ecstatic if I get to that 100k mile landmark! Alot of money for sure but less than a similar Nickies/JE set.

I've really struggled to get this motor running and really pleased to now have an alternative solution that based on engineering principles should be a much more robust solution. So I'll be ordering the JB solution tomorrow!

targa72e · 07-21-2019, 12:05 PM

HI Andy,
Were your 100MM nickies bore in or slip fit?
Thanks,
john

Andy@Altitude · 07-22-2019, 08:00 AM

John,
These were bore in so spigot dia is 105mm

K24madness · 07-22-2019, 07:37 PM

I am disappointed to hear the Nickies are that fragile. I was toying with the idea of “upgrading” during my last build. What concerned me most was the expansion tendency of dense billet materials. I stuck with stock and had near zero leak down at 5k miles. Plenty of track and boost runs.

stanglife · 07-23-2019, 05:15 AM

Is this not a concern with NA applications?

MBruns · 07-23-2019, 08:30 AM

I recently disassembled a 3.0 based engine with 100mm Nickies that were slip in at 103mm, I measured them carefully and was happy to see they were very straight and round, these were run close to 10,000 miles street/track, as it turned out we rebuilt the engine with a GT3 crank and used the cylinders again with custom pistons/rods, CP pistons at 10.5 CR, running this on the engine dyno you can tell a lot about cylinders and ring seal watching the clear breather hose activity during a pull and as the engine and head temp rise, these cylinders worked very well.

Thanks, Mike Bruns

lvporschepilot · 07-23-2019, 09:57 AM

Just to add to the database, while I haven't torn either of these engines down yet, I have not one, but 2 twin plug 911 engines running 92mm iron liners with JE high comp pistons and DC65 cams. Both are 2.8s, one is track use-only with MFI, other is EFI ITB. Both run extremely well, neither overheats. Bhp is likely around 270-280. The track-use engine will likely come apart first, really wanting to see how things held up.

MBruns · 07-23-2019, 10:24 AM

Did you use the JB cyls on your 2.8's ? how long have you been running those
Mike Bruns

lvporschepilot · 07-23-2019, 11:22 AM

Quote:

Originally Posted by MBruns

Did you use the JB cyls on your 2.8's ? how long have you been running those
Mike Bruns

Both running 92mm liners from AA. Track car is on its 2nd season now, has about 50 hours and is MFI. Engine and MFI were already well set up for what I did, which was just a refresh and swapping the existing worn 92mm liners for the cheapo AA liners and JE pistons. It was done entirely as an experiment just to see. Well, we've seen, and it goes fine. You may have seen this as well, but based on what I've seen, these engines carry most of their heat in the heads, which are alum as they should be. I'm primarily a Ferrari guy but they're the same way. Mine has a little over 1000 miles on it so it's not a great representation of a motor being 'beaten within an inch of its life' on the regular like a track engine, but mine even with a standard 44 row Setrab oil cooler in the wheel well it doesn't go about 210 or so, ever. I think the real result will be once the track motor is ready for a tear down, but so far so good.