Boost and hp #s
- Thread starter HANDSOM E
- Start date
quadzillaracer
New member
In a perfect tune at sea-level "around" 225 hp with the 66.
quadzillaracer
New member
Hey Dan, nothing is set in stone on what a 2-stroke turbo engine should make p/lb of boost. The horsepower number that I provided HANSOM E was what my old 800 set up made with my Aerodyne Series 66 turbo @ 9-psi of boost on VP C-16.
Getting back to your question, there are many factors to consider when figuring hp/boost numbers. First off, displacement and number of cylinders plays a huge factor in these numbers; the larger the displacement the wider the spread is for hp p/lb of boost. For example only, a 750cc Vmax-4 engine that is forced induction might produce 8 hp p/lb of added boost pressure; now a 1000cc Vmax-4 set up will produce closer to 11.5 hp/ p lb of boost. The engine is nothing more than an air compressor. Next, turbo sizing is absolutely crucial based upon the selected pressure ratio that you plan to operate at. In my previous dyno testing "example again", my Vmax-4 with big bore race engine was producing around 360 hp @ 20-psi of boost, instant spool and the Aerodyne Series 66 was off the map but, IAT were still in check and it was happy. Next same engine set up, but with a larger Garrett GT3071R Turbo rated for 46 p/p min (460) hp, this set up actually made about 10-hp less at the same 20-psi of than my smaller Series 66 and a decent amount of lag. So throwing a "bigger" turbo on isn't always the answer as many guys think. Now, the little Series 66 had its tongue hanging out at 20-psi of boost and was on barrowed time; but as I increased boost psi on the GT3071R, and moved the pressure ratio to the "comfort zone" on the compressor map this turbo began to shine and make great power over the Series 66, which could produce no more efficiently. So, to sum this up from the example, a "larger" turbo that is not running in it's "efficient zone' of the compressor map can alternate the hp/ p/lb of boost, same as an exhaust turbine housing will. Hope this helps!
Justin
Getting back to your question, there are many factors to consider when figuring hp/boost numbers. First off, displacement and number of cylinders plays a huge factor in these numbers; the larger the displacement the wider the spread is for hp p/lb of boost. For example only, a 750cc Vmax-4 engine that is forced induction might produce 8 hp p/lb of added boost pressure; now a 1000cc Vmax-4 set up will produce closer to 11.5 hp/ p lb of boost. The engine is nothing more than an air compressor. Next, turbo sizing is absolutely crucial based upon the selected pressure ratio that you plan to operate at. In my previous dyno testing "example again", my Vmax-4 with big bore race engine was producing around 360 hp @ 20-psi of boost, instant spool and the Aerodyne Series 66 was off the map but, IAT were still in check and it was happy. Next same engine set up, but with a larger Garrett GT3071R Turbo rated for 46 p/p min (460) hp, this set up actually made about 10-hp less at the same 20-psi of than my smaller Series 66 and a decent amount of lag. So throwing a "bigger" turbo on isn't always the answer as many guys think. Now, the little Series 66 had its tongue hanging out at 20-psi of boost and was on barrowed time; but as I increased boost psi on the GT3071R, and moved the pressure ratio to the "comfort zone" on the compressor map this turbo began to shine and make great power over the Series 66, which could produce no more efficiently. So, to sum this up from the example, a "larger" turbo that is not running in it's "efficient zone' of the compressor map can alternate the hp/ p/lb of boost, same as an exhaust turbine housing will. Hope this helps!
Justin
Jabber800
New member
No doubt the efficency of the charger and where your trying to run it on the compressor map
will have huge effects on how well the charger performs. I was just tryingvto get an idea
on how efficient these two strokes are on boost compared to a 4 stroker.
I may tackle a 2 stroke build next season. I think I would build it as a fuelie though.
will have huge effects on how well the charger performs. I was just tryingvto get an idea
on how efficient these two strokes are on boost compared to a 4 stroker.
I may tackle a 2 stroke build next season. I think I would build it as a fuelie though.
quadzillaracer
New member
Yeah, they can be fun! I actually have a fuel injection system pretty much finished for the Vmax-4 using 46mm throttle bodies off an Arctic Cat 1000cc twin. Spacing is all finished with custom intake adapters to fit. I've talked to Jim at OSP and he would like to work with my sled and install the BS3 ignition on it; but I've been busy with work and I like the forgiveness of my carb set up in a boosted application, I've got it figured out pretty well to make the big power, but I do want to get the standalone fuel injection system complete. Skinner is waiting for me to finish it up to install one on his 800 Open Mod. I should have it complete by late-summer. Fuel Injected and Boosted Vmax-4!
turch
VMAX4 Racing Moderator
quadzillaracer
New member
Well, I just wrote a long post Turch, but it disappeared when I hit post. Anyways, it's a real limited market but I hopefully can have it ready for limited sale by late-summer/early fall. As per my last conversation with Jim, he needs a crankcase for setting up the triggers for the 2-stroke and measurements for building the harness. Throttle bodies and adapters are done, now I have to finish up the fuel rail as I'm adding bungs for (4) additional injectors to be used on the boosted application.
quadzillaracer
New member
Are you using Dave Marshall's standalone system now? Are you going to build a boosted Vmax-4 or a big displacement SRX set up?
Jabber800
New member
No I'm not using Dave's system. He uses the Autronics. I wanted to be different and try something else so I have gone my own route. I also have been working on a new supercharger system for the apex's and the viper's as well. I hope to be running one of these kits this winter in the nbssr cct for testing. Do you plan to get out to any nssr events this year?
quadzillaracer
New member
Yeah, NSSR is holding a sanctioned race about 6-hrs from me in Fairmont, MN around the 25th of January so I'm planning on racing at that event. If it works out, I'd also like to race at the year end Winterfest NSSR race in Chetek, WI; but I'll have to see because we are doing lots of mountain riding with the turbo sleds too, and have quite a few rides planned. I just want to put this 20-year old Vmax-4 deep into the 170's in 1000' for its anniversary! That's the goal.
quadzillaracer
New member
Thanks Dan! If it all holds together like it should, then it should definitely lay down a big number in the 1000'. 140 mph is moving in 1320'; we have a few Pro Stock 800 Mach Z's that are knocking on the door of 140 mph in 1000' at NSSR.
I always thought it would be cool if the stars aligned and we could come up with an area that was "somewhat" close for travel, and have an NSSR vs NBSSR speed run shootout and run the sleds for 1320'. We have guys that want to travel north into Canada for an NBSSR speed run, but unfortunately some of the crews have guys with DUI's and can't cross the border into Canada to race. Maybe one day things will workout for everyone and we can make the trek north.
I always thought it would be cool if the stars aligned and we could come up with an area that was "somewhat" close for travel, and have an NSSR vs NBSSR speed run shootout and run the sleds for 1320'. We have guys that want to travel north into Canada for an NBSSR speed run, but unfortunately some of the crews have guys with DUI's and can't cross the border into Canada to race. Maybe one day things will workout for everyone and we can make the trek north.
Jabber800
New member
I am working towards bringing a couple sled s down for a 1000 ft event. Our problem is set up changes a lot. We are not allowed chissels so running 1000 ft would mean re studding as well as new head designs, timing and fuel requirements. When we dropped down from 2000 ft to 1320 I changed everything about my set up and we are now faster in 1320 than we where in 2000. The distance really affects the set up of the hole sled.
quadzillaracer
New member
99% of the NSSR racers do not run chisels in their tracks for speed runs, and if your running a Dayco or Camoplast speed band, ice chisels are illegal. 2000' was just a ridiculous distance to run for a magnitude of reasons from track integrity (centrifugal force/ ballooning of track), to the safety of the racers; they are lucky no one ever got killed up there in that type of distance, most of the time if you look at the archived speeds the NSSR 1000' guys were running nearly the same as the 2000' NBSSR guys. I don't think timing and head design is going to alter much going from 1320' distance to 1000'; realistically most sleds will cover the last 320' of track in around 1.5-seconds or less pending. I can, however, see how timing and head design would be a major factor going from 2000' down to 1320', because of the added distance, generated heat, and the amount of time that poor motor is pegged for 2000', everything is working against you after 1/4 mile.
Whospartin
Banned
How much boost on a daily basis can the LS and GSR engines handle if they had a block guard and a thicker head gasket? Can the LS engine handle much more than the GSR?