04:04:47am, Monday, April 29, 2024
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Allison Mod Combinations
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IH 5488
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I will admit I don’t know a lot about Allison engines. I’ve been watching a lot of old videos at the farm show and one things I can’t figure out is why a lot of people never turbo charged the Allison engine or if they did they would turbo charge the one engine but not the other to me that doesn’t make sense but I know very little about mods. I was also wondering that while these engines are now pretty hard to find with the newest turbo technology how come you don’t see people TwinTurbo these tractors with say a 5 inch turbo on each side. Will the bottom end just not take it I know there has to be a reason. But with these cubic inches you would think they could spin two big turbos and make the Allison motors competitive again. |
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Re: Allison Mod Combinations
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Moderator Registered: 07/06/2008 Posts: 1,347 |
In the 1980s several guys ran turbo allisons, most prominently Gardner Stone with a triple turbo allison. Wayne Longnecker ran a tough twin allison with turbos in the early to mid 90s.
Gardner said in an interview that turbos make lots of power but they also make lots of parts. He probably got tired of going through so many parts when he built the turbine tractor. Edited 1 time(s). Last edit at 02/09/2023 11:54AM by The Original Michael. |
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Re: Allison Mod Combinations
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Face in crowd
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I'm just a fan. No expert, but I love Allisons. I asked Sascha that same question on here probably 15 years ago. He gave me an informative answer, but the bottom line, in his words, was "parts on the track". |
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Re: Allison Mod Combinations
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And don't forget Richard Rockefeller.
Problems with these old aero v12 engines and turbos in a nutshell. The orig carburator could easily handle the nonlinearities of the crank driven centrifugal supercharger. The mech controlled alc injection system couldn't. And to increase the problem, people even enlarge the disadvantageous nonlinear characteristic by swapping from the orig radial blower to turbos. The reliable operational engine speed band gets quite narrow, the risk to be too rich below peak power or to be far too lean beyond partial load is omnipresent. With all its consequencies, which were quite common visible back in that days, and a lot of broken parts. Nowadays state of the art technologies holding two things worth to look at. Latest turbos are a bit more efficient, creating less heat, and it's not longer needed to compensate manifold air temp by adding that excessive much more fuel and/or water. Nonlinear air mass flow of centrifugal chargers, independent if crank driven (orig, or pro charger) or turbo, today is much easier to handle with EFI than with mech controlled injection systems of the 70s-90s. |
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Re: Allison Mod Combinations
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Registered: 03/27/2008 Posts: 1,145 |
You've nailed it!
The reason why the Green Monsters are not running turbos (they absolutely could with the EFU set up they have now) is plain and simple: Weight. The homemade superchargers are just way lighter than turbos. We had two big choo choos in the shop, put them on a scale and sold them. Floating Finish - the German Tractor Pulling Web Show and EU Live Streams: [www.youtube.com] Edited 1 time(s). Last edit at 02/16/2023 12:59AM by Sascha. |
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Re: Allison Mod Combinations
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Registered: 04/04/2008 Posts: 1,522 |
The only restriction an allison should have is NO NITRO anything else goes !! |
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Re: Allison Mod Combinations
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Richard Rockefeller
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My original single engine turbo charged allison ran awesome. When I built the twin the second engine would not transition when opening the throttle. I took the tractor to a well known successful alcohol SS puller with a flow bench. I asked him to take one check valve, the same valve, at a time off each engine. He said, I can take them all off at the same time and put them back. When he got done, he said oh you do not need these check valves. When summer came NEITHER engine ran correctly!
At the time I was not familiar enough with the Hilborn injection to correct the issue. After I had made the commitment to V8s I realized the problem was the bypass he had removed. I think the twin allison turbo charged tractor would be awesome! |
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Re: Allison Mod Combinations
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Moderator Registered: 03/19/2018 Posts: 664 |
Yours would have been AWESOME had you been able to get that right. What am I saying, it was awesome anyway!
Hope you are well. CP |
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Re: Allison Mod Combinations
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old puller
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Parts on the track and hard to get hooked to the track. Wheels don't hook the same compared to running the blower with a pile of Tork. |
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Re: Allison Mod Combinations
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Yes the Allison does have a statistical advantage when thinking of how large the engine is. And it does have some very good characteristics for great power potential. The greatest problem with the Allison is the rod bearing design, the blade and fork rod design limits the bearing surface area for the blade rod. Guys have offset the banks of the engine to utilize a standard style connecting rod and bearing but very few took it far enough to show its potential. In the past lots of parts have ended up on the track with turbo allisons, I chalk this up to several circumstances, poor bearing design, fuel injection technology, ignition technology, turbo technology, and lack of data. With technology today many of those problems have already been solved. Today the biggest issue is there are very few individuals that are capable and willing to push the limits of the platform. When there is a very small group working on R&D it takes time and most importantly $$$.. there is continual improvements made within the Allison community each year. The most evident of this is the green monster team in Germany, they have a great group of individuals that pour their heart and soul into maintaining competitiveness with their equipment. I think there will be several great advancements on the allisons here in the states that may revive some of their competitiveness made within the next several years. The idea of putting together an allison with two of today's modern prostock turbos and efi has been thrown around our shop several times.. I do think it has some major potential, there would have to be a significant investment made to do it right and making it all happen but would be neat if it were to work. Today i can throw a rock and hit a 3000hp hemi made by xyz manufacturer and have parts here for it whenever i want, all at a pretty reasonable price for what you are getting. The people that have the money to spend and willingness to build a tractor and compete are gunna go that route.. It's not very often that you come across the people that have the funds, brains, and willingness to do something different. Now there are people out there like that but.. they are smart enough to take the path of least resistance and not put themselves through the headache of an Allison. Lets look at two of the greatest examples of Allison pullers in the states who are still pulling, Longnecker and Bollinger's both now have hemi powered tractors. That says a lot. People like me do have the aspirations to revive the Allison's competitiveness on a national scale i think the resources and people involved in our team have the capability to do so but time and money always seem to get in the way. Maybe someday but time keeps ticking |
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Re: Allison Mod Combinations
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plb
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Blake, you are right about the Green monster team in Germany, Have been there and watched them and they do a super job with the Allisons! Almost ironic that a team from Germany can make them run like they do, but in the states, everyone has givin up and moved on to V-8`s. I will say though, that lite mod they got is one bad ass tractor!!! Got to watch it close up in Zwolle, NL, 2020 and it was a beast!! The twin Hemis of Borr`s had all they could do to stay close!! |
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Re: Allison Mod Combinations
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rules
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The rules committee has restriction on the Allisions. |
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Re: Allison Mod Combinations
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Modpuller
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Don’t see turbo Allison’s because they don’t really fit anywhere with current rules. 1 turbo Allison is too much for a single hemi class, but 1 turbo Allison would struggle to be competitive in a twin hemi class. 2 turbo Allison’s in the NTPA mod class might be competitive, but it’s not legal. Drivability would start to really be an issue with 3 turbo Allison’s in the open class and it would struggle to make weight anyways.
With modern turbos and well tuned EFI, a lot of the durability issues of the past should be reduced. And with greater parts availability now than in recent years, with new production pistons, rods, and bearings there may be more people willing to lean on this platform again that may have been held back by parts that hadn’t been produced since the late ‘40s. |
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Re: Allison Mod Combinations
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Registered: 09/14/2021 Posts: 16 |
Starlight Express 3 (Italian triple Allison heavy mod built in UK).
Few years ago tried the turbo way, but never had results. Currently building a single Allison light mod with prochargers. |
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Re: Allison Mod Combinations
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I honestly never understood the rules as they are. To me it's so outdated. Probably would have made sense in the 80s or so, where people with two BBC fit into the same light mod class as people with one Allison. Horsepower per weight were somehow in the same range, if you squeeze out a big V12 of 1710 cu.in to reach in best case 2800-3000hp, with tons of reliability issues, effort etc. Compared to a twin V8 cookie cutter setup, which was easily able to get beyond 1500hp per unit, it already has been kind of a disadvantage. And then, 30+ years later, when the V8 typically making between 2500-3000hp (bread&butter, not top notch!) per unit, this disadvantage went just extreme.
Why they don't skip that stupid rules? Are there so many people out whom fear an upcoming dominance of V12 aircraft engines?!? Even if it were allowed to compete with 2 Hemis of around 3000hp each against to well prepared old V12s of 3000hp each, it would be still on the safe side for the V8s because of their less weight, dimensions, abilities for COG positioning etc. |
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Re: Allison Mod Combinations
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Registered: 04/04/2008 Posts: 630 |
Carlsson,
In the NTPA RN level the Allison rules were opened up several years ago to allow larger supercharger wheels. After the change we ran our two twin Hemi tractors against the Top Gun tractor with two Allison's. My tractor just missed the pulloff my wife's tractor and Craig driving Top Gun got into the pulloff. Craig ran neck and neck with us that night in Wauseon. I think if they ran with us week after week they would be right there with our twin Hemi's. We also ran against the Boxler twin Allison in Langford, NY, Tarry won the early session Ken Miller won the second session with Hans second and Tarry third. It looks pretty even to me. Not to mention that Brian Deikman kicked our butts many times in both the RN classes and the Lt. Unlimited, had he been able to run newer style tires in the Lt. Unlimited I'm not sure we could have ever gotten past him. S'no Farmer |
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Re: Allison Mod Combinations
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Loto Winner "IN MY DREAMS"
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Looking forward to building billet Allison's with proper block stagger and prochargers. gonna be sweet! |
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