The Crankshaft thread non Crankshaft discussion
11-10-2015, 02:53 PM
#1
Rennlist Member
Thread Starter
The Crankshaft thread non Crankshaft discussion
Nice crankshafts, good to see this project moving forward.
I think that the 928 S4 rotating assembly is very strong and great for relatively low rpms. (I don't have anything good to say about that of the GTS...) We're pushing it very hard in terms of gas pressures with the turbo cars, and it just keeps holding. What makes the 928 rotating assembly super reliable at 6000 rpm is also its weakness at say 8000 rpm: It's very heavy. So it makes sense that if someone wants to go to 8000 rpm, a lighter rotating assembly is needed.
8000 rpm is not a problem from engine breathing perspective now that we have ITB options to replace the stock S4 intake, again which is great at 5000 rpm but "sucks hairy *******" at 7000 rpm.
I think that the 928 S4 rotating assembly is very strong and great for relatively low rpms. (I don't have anything good to say about that of the GTS...) We're pushing it very hard in terms of gas pressures with the turbo cars, and it just keeps holding. What makes the 928 rotating assembly super reliable at 6000 rpm is also its weakness at say 8000 rpm: It's very heavy. So it makes sense that if someone wants to go to 8000 rpm, a lighter rotating assembly is needed.
8000 rpm is not a problem from engine breathing perspective now that we have ITB options to replace the stock S4 intake, again which is great at 5000 rpm but "sucks hairy *******" at 7000 rpm.
11-10-2015, 03:02 PM
#2
Archive Gatekeeper
Rennlist Member
Rennlist Member
i have been running the 6.5 liter with all sorts of tires on the street for many years and with 420 ft-lbs of torque, i never even come close to seeing wheel spin, unless im in 1st gear .
Is your clutch slipping? Maybe you're rich as **** at 3800 rpm and don't know it?
so the question becomes do we need this racing crank, if we dont have the motor top end to support any more power at the higher RPM?
doesnt the 928 have an oiling problem
Last edited by Rob Edwards; 11-10-2015 at 03:21 PM.
11-10-2015, 04:30 PM
#3
Rennlist Member
Thread Starter
You don't/can't get wheelspin in 2nd gear? Is your clutch slipping? Maybe you're rich as **** at 3800 rpm and don't know it?
The limitations at the top end are a combination of the intake to feed it, having the cams, springs and lifters to safely handle 7000+ rpm, and the ability to properly control fueling at those rpm. Between Greg's parts bin and the most recent versions of ST Alpha N that allow editing of the rpm axis, we can begin to address the limitations. It'll take some engine dyno time to do it safely, but that's part of the fun.
Yes. Greg's got a new bit for that as well.
[im/img]
Is your clutch slipping? Maybe you're rich as **** at 3800 rpm and don't know it?The limitations at the top end are a combination of the intake to feed it, having the cams, springs and lifters to safely handle 7000+ rpm, and the ability to properly control fueling at those rpm. Between Greg's parts bin and the most recent versions of ST Alpha N that allow editing of the rpm axis, we can begin to address the limitations. It'll take some engine dyno time to do it safely, but that's part of the fun.
Yes. Greg's got a new bit for that as well.
[im/img]
I start EVER race in 2nd gear about 4500rpm and floor it as fast as i can an have never got the wheels to spin!! in the rain.. yes..
the mixture is irrelevant.... i have 420 ft-lbs from 3500rpm to 4500rpm. but if you really want to know, mixtures are in the safe range in the 11s to 12s. you have seen my dynos.
back to the intake... you say springs, cams to safely handle 7000rpm. . again, if you dont have an intake to make power there, why bother? stock cams and springs can handle the 6800rpm range. probalby with 1mm more lift than stock making that a "race class cam". mixture is easy to get close to make things safe. optimizing is the trick, but thats the extra hp you would get by proper tune.. im just talking about the basic HP potential and shape of the HP curves.
back to wheel spin.... you can watch my hundreds of videos to see that there is no wheel spin with 420rwt. or i can go do a street video on cold tires to show it as well. unless you rev the engine and then you dump the clutch , there should be no wheelspin.. maybe your clutch is slipping.
11-10-2015, 05:25 PM
#5
Rennlist Member
Thread Starter
"I dont have wheel spin at WOT in 2nd gear" is much different than "i cant make my wheels spin", or "i have wheel spin and its a problem". which do YOU think is a (car) problem?
it also makes no sense to worry about dumbing down torque and keeping the hp the same or even rasing that. if you are at 3500rpm and have wheel spin, you will have LOT more wheel spin in a lower gear at 5500rpm with more HP !
Here is a stock ECU and intake system on the 6.5 liter. i dont see how a high perforamnce crank cabable of running 7500rpm will do anything without major attention to cams and intake mods. as you can see, the HP curve is arc'ed nicely from 4500 to 6500rpm. any higher RPM capability without changing the breathing of the engine would be a waste of time.
11-10-2015, 06:52 PM
#6
Archive Gatekeeper
Rennlist Member
Rennlist Member
I hesitate to ask this, but don't you have 2.2 R&P in your racer?
11-10-2015, 07:38 PM
#7
Archive Gatekeeper
Rennlist Member
Rennlist Member
So here are two dyno pulls on my 6.5 stroker with stock intake, running Alpha N, with headers and exhaust, SAE corrected. I have 20 extra rwhp than you, not sure where that's coming from but maybe that's the difference in terms of wheelspin? Or you're a seasoned racer who knows that wheelspin is wasting time, and I'm just a street punk hoonaholic? 
Trending Topics
11-10-2015, 07:56 PM
#8
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
11-10-2015, 08:10 PM
#9
Rennlist Member
Thread Starter
the 2nd gear of a 2.2 vs a 2.73 rear end isn't 2.73 / 2.22 its only a 16% difference.
in fact, if you are in 2nd gear and have issues at 3500rpm, i can be at 4500rpm in 1st and be at 28% more torque at the rear wheels! (and not reallly have any issues). i do this sometimes at turn 11 at laguna in close battles with tighter lines. never been an issue. lots of video of that as well.
If you have a problem keeping the wheels underneath you with 420rwht at 30-40mph, then why not just not press the gas a little less.
so, i guess what Greg is trying to do is make the engine more higher reving and less torque down low, so you can mash the gas around town, and not worry about wheel spin. but when in race mode you take it up to 7500rpm for higer max rear wheel forces compared to lower HP'ed other cars with higher torque in the mid and low range.
The problem with this idea, (and ive seen this too at the race track) is that the average HP is what wins out.
the best example i can think of is when i first raced the stroker vs a supercharged S2000 with 420rwhp. (vs my 372 rwhp 928). i was able to win the race due to my average hp being greater .(more area under the curve) he had a post shift HP of less than 220hp and a peak hp of 420 (ave 320). the 928 stroker was 350 at the low end and 373at the high end, (ave 360). in the end, i raced like i had a 40hp advantage and he had no chance as we were braking and cornering at similar speeds.
so, i dont understand the need to lower torque in the mid range , regardless of the gear box . Heck, if this is a REAL problem, just take the flappy out if you have a stock intake.. OR, retard the cam and ignition timing and tune it out.
in fact, if you are in 2nd gear and have issues at 3500rpm, i can be at 4500rpm in 1st and be at 28% more torque at the rear wheels! (and not reallly have any issues). i do this sometimes at turn 11 at laguna in close battles with tighter lines. never been an issue. lots of video of that as well.
If you have a problem keeping the wheels underneath you with 420rwht at 30-40mph, then why not just not press the gas a little less.
so, i guess what Greg is trying to do is make the engine more higher reving and less torque down low, so you can mash the gas around town, and not worry about wheel spin. but when in race mode you take it up to 7500rpm for higer max rear wheel forces compared to lower HP'ed other cars with higher torque in the mid and low range.
The problem with this idea, (and ive seen this too at the race track) is that the average HP is what wins out.
the best example i can think of is when i first raced the stroker vs a supercharged S2000 with 420rwhp. (vs my 372 rwhp 928). i was able to win the race due to my average hp being greater .(more area under the curve) he had a post shift HP of less than 220hp and a peak hp of 420 (ave 320). the 928 stroker was 350 at the low end and 373at the high end, (ave 360). in the end, i raced like i had a 40hp advantage and he had no chance as we were braking and cornering at similar speeds.
so, i dont understand the need to lower torque in the mid range , regardless of the gear box . Heck, if this is a REAL problem, just take the flappy out if you have a stock intake.. OR, retard the cam and ignition timing and tune it out.
Last edited by mark kibort; 11-11-2015 at 01:58 PM.
11-10-2015, 08:12 PM
#10
Rennlist Member
Thread Starter
11-10-2015, 08:30 PM
#11
Rennlist Member
Thread Starter
So here are two dyno pulls on my 6.5 stroker with stock intake, running Alpha N, with headers and exhaust, SAE corrected. I have 20 extra rwhp than you, not sure where that's coming from but maybe that's the difference in terms of wheelspin? Or you're a seasoned racer who knows that wheelspin is wasting time, and I'm just a street punk hoonaholic?
wheel spin should be the max torque values and the gear ratio too, albeit about 50+ft-lbs at 4000rpm or so equiv, but yes, it does require a skilled foot in 1st, but not so much so in 2nd. i have a lot of video of Anderson coming out of turn 11 with his foot in it in 2nd and not spinning the wheels.
if you put some steering input, and then WOT, you can get most any car to spin in 2nd briefly.
so, alpha N , is like the BMW tuning stuff? cams 85s or GT?
single disc clutch? or racing clutch?
also, what kind of dyno? mustang dyno or a big drum dynojet 248e?
if the same... i would like to find that 25hp or so at 5500rpm that ive lost to near equal power and torque at 4500 and that stays down as the RPM goes to approaching redline.
11-10-2015, 09:22 PM
#12
Archive Gatekeeper
Rennlist Member
Rennlist Member
AFR plots on a chassis dyno don't mean much, post-cat. Do you have cats on your racer?
Cams were GT cams, base circle reduced with lash caps. Clutch is carbon dual disc.
I don't know what kind of dyno it is, it's whatever this is. I presume this is a 'big drum' dyno:
http://www.superiorautomotive.com/Dy...%20Angeles.htm
Alpha N is just the sharktuner, but it doesn't use the MAF, just a throttle position sensor and an air intake temp sensor.
Cams were GT cams, base circle reduced with lash caps. Clutch is carbon dual disc.
I don't know what kind of dyno it is, it's whatever this is. I presume this is a 'big drum' dyno:
http://www.superiorautomotive.com/Dy...%20Angeles.htm
Alpha N is just the sharktuner, but it doesn't use the MAF, just a throttle position sensor and an air intake temp sensor.
11-10-2015, 10:24 PM
#13
Former Vendor
thanks Greg.. that makes it clearer, but still a little confused on the goal. maybe you can help me understand.
so you are saying you are not going the displacement direction because it provides such torque that one customer "rob" spun his large rear tire clad GTS at low RPM? that seems a little strange, as i have been running the 6.5 liter with all sorts of tires on the street for many years and with 420 ft-lbs of torque, i never even come close to seeing wheel spin, unless im in 1st gear .
also, with the GTS or any other 928, you get max torque at about 4000rpm. sure, we can get wheel spin in 1st.. but you need to floor the car... in 2nd, at 4000rpm you also need to be WOT, and in 3rd and beyond, there is not enough torque to provide spin unless you are in the rain
by taking away displacement and going back to GTS specs and making things lighter, that doesnt in itself, provide more power. 5-10lbs off a crank , as far as power goes, doesnt do very much, but sure, reving your engine for downshifts or reving the engine at a stoplight to impress friends, sure, its much better. on the dyno though, and as dynos measure HP, its over a time period. after 1st gear the rate of RPM is relatively slow, so 5lbs off a flywheel, crank , etc, doesnt buy that much in terms of HP. (something like 20hp in 1st gear, 10hp in 2nd gear, 5hp in 3rd gear 1.5hp in 4th gear.....etc)
I understand by using your speical light pistons, and smaller journaled crank you then have less bearing speeds and less forces on the bearings at high RPM and better oiling... but if you are going to use this masterpiece of a crank design, its really to get more hp at higher RPM. if you dont change anything on the intake, how is that possible engines dont make a lot more power just by having lighter components alone.
ok my question regarding your desire to "move forward" are you going to address the 928 age old question of are we ever going to have a good NA intake that brings the 928 intake system into the 21st century , where it is common place for the crappy MUSTANGS and Aston Martins 4.3 liter or 5 liters to make over 450rwhp with very little modifications? it seems to be most all intake system related.... and yes, they are twisting up to near 8krpm now and have designed their wet sump systems to survive high g loading and high rpm both.
so the question becomes do we need this racing crank, if we dont have the motor top end to support any more power at the higher RPM? after all, in looking at the HP torque curves of say, mark A's motor, it didnt make much more sense to drive the RPM above 7000rpm . even with the new intake, it didnt seem like going higher than 7200rpm was going to pay much in dividends.
It would be nice to see a S4 intake that bolted on stock, GTS and 6.5 liter engines that gave the kind of gains we saw in marks car, going from 420rwhp to 520rwhp with very little tweaking of the stock ECU components and fuel maps.
also, i do think when folks are evaluating their options, if you had the ability to use this crank or your own version of the GTS crank, to make any S4 into a GTS by even using the same pistons , it would be attractive. suddenly each rebuld could be a GTS conversion with only the cost of crank and rods. sure the GTS and more so , the S4 pistons are heavy, but again, the power band of these engines makes use of the heavier components quite well, in that they would rarely see RPM over 6400-6600rpm ..... especially, if this is designed for street use as you say. this even makes their marketability even greater. the other two cranks 6.5 liter and the light weight racing 5.4 to 5.8 liter set ups could be used for racing or just plain high quality builds as they often are in the street performance world.
so you are saying you are not going the displacement direction because it provides such torque that one customer "rob" spun his large rear tire clad GTS at low RPM? that seems a little strange, as i have been running the 6.5 liter with all sorts of tires on the street for many years and with 420 ft-lbs of torque, i never even come close to seeing wheel spin, unless im in 1st gear .
also, with the GTS or any other 928, you get max torque at about 4000rpm. sure, we can get wheel spin in 1st.. but you need to floor the car... in 2nd, at 4000rpm you also need to be WOT, and in 3rd and beyond, there is not enough torque to provide spin unless you are in the rain
by taking away displacement and going back to GTS specs and making things lighter, that doesnt in itself, provide more power. 5-10lbs off a crank , as far as power goes, doesnt do very much, but sure, reving your engine for downshifts or reving the engine at a stoplight to impress friends, sure, its much better. on the dyno though, and as dynos measure HP, its over a time period. after 1st gear the rate of RPM is relatively slow, so 5lbs off a flywheel, crank , etc, doesnt buy that much in terms of HP. (something like 20hp in 1st gear, 10hp in 2nd gear, 5hp in 3rd gear 1.5hp in 4th gear.....etc)
I understand by using your speical light pistons, and smaller journaled crank you then have less bearing speeds and less forces on the bearings at high RPM and better oiling... but if you are going to use this masterpiece of a crank design, its really to get more hp at higher RPM. if you dont change anything on the intake, how is that possible engines dont make a lot more power just by having lighter components alone.
ok my question regarding your desire to "move forward" are you going to address the 928 age old question of are we ever going to have a good NA intake that brings the 928 intake system into the 21st century , where it is common place for the crappy MUSTANGS and Aston Martins 4.3 liter or 5 liters to make over 450rwhp with very little modifications? it seems to be most all intake system related.... and yes, they are twisting up to near 8krpm now and have designed their wet sump systems to survive high g loading and high rpm both.
so the question becomes do we need this racing crank, if we dont have the motor top end to support any more power at the higher RPM? after all, in looking at the HP torque curves of say, mark A's motor, it didnt make much more sense to drive the RPM above 7000rpm . even with the new intake, it didnt seem like going higher than 7200rpm was going to pay much in dividends.
It would be nice to see a S4 intake that bolted on stock, GTS and 6.5 liter engines that gave the kind of gains we saw in marks car, going from 420rwhp to 520rwhp with very little tweaking of the stock ECU components and fuel maps.
also, i do think when folks are evaluating their options, if you had the ability to use this crank or your own version of the GTS crank, to make any S4 into a GTS by even using the same pistons , it would be attractive. suddenly each rebuld could be a GTS conversion with only the cost of crank and rods. sure the GTS and more so , the S4 pistons are heavy, but again, the power band of these engines makes use of the heavier components quite well, in that they would rarely see RPM over 6400-6600rpm ..... especially, if this is designed for street use as you say. this even makes their marketability even greater. the other two cranks 6.5 liter and the light weight racing 5.4 to 5.8 liter set ups could be used for racing or just plain high quality builds as they often are in the street performance world.
I openly discuss about 5% of what I'm up to at any given time.....and about .05% of what I'm thinking about doing.
Let's just say that there is a plan....and a path to get where we are headed.
11-11-2015, 12:51 AM
#14
Archive Gatekeeper
Rennlist Member
Rennlist Member
Mark, while I'm dredging up old dyno curves- here's my stroker with stock intake vs. the first iteration of Greg's intake, both running Alpha N as described earlier. There was a bunch of re-tuning in order to dial in 44 lb injectors vs. the 30 lb with the stock intake, but the bottom line was ~50 hp and ~45 torques. (2 pulls from each condition). Great result from 4000 to 5500 but it falls off above that, as the intake flow got wonky.
This new Zombie motor gets a dry sump setup, different springs, a bit more cam lift (and different LSA) feeding 5.8 L vs. the 6.5L Zombie 1.0's cams, and a revised GB intake, based on the dyno experiments on my car and Jim Corenman's.
This new Zombie motor gets a dry sump setup, different springs, a bit more cam lift (and different LSA) feeding 5.8 L vs. the 6.5L Zombie 1.0's cams, and a revised GB intake, based on the dyno experiments on my car and Jim Corenman's.
11-11-2015, 02:20 AM
#15
Rennlist Member
Thread Starter
Mark, while I'm dredging up old dyno curves- here's my stroker with stock intake vs. the first iteration of Greg's intake, both running Alpha N as described earlier. There was a bunch of re-tuning in order to dial in 44 lb injectors vs. the 30 lb with the stock intake, but the bottom line was ~50 hp and ~45 torques. (2 pulls from each condition). Great result from 4000 to 5500 but it falls off above that, as the intake flow got wonky.
This new Zombie motor gets a dry sump setup, different springs, a bit more cam lift (and different LSA) feeding 5.8 L vs. the 6.5L Zombie 1.0's cams, and a revised GB intake, based on the dyno experiments on my car and Jim Corenman's.
This new Zombie motor gets a dry sump setup, different springs, a bit more cam lift (and different LSA) feeding 5.8 L vs. the 6.5L Zombie 1.0's cams, and a revised GB intake, based on the dyno experiments on my car and Jim Corenman's.
I remember seeing the GB intake a long time ago on a thread.. were these the dyno runs. i remember seeing 450ish rwhp.
what do you mean, "it falls off" torque has to fall off from there, otherwise HP will continue to rise... you have a pretty broad HP curve and thats ideal . huge gains off the stock intake and GT cams. zombie cams 1.0 were only 1mm more lift than GT, right? why did you need 40lb injectors vs the 30.. wouldnt 30 do the job with the shark tuner?
was this intake the one off master piece ? are there more for the rest of us?
what happened to that stroker engine? is that in your street car?
the new stroker 5.8 will have more cam so expected hp might be close, but possibly higher reving as well?
can you post pics of the intake.
I think the holy grail would be to have an intake, that could just bolt on the heads, use the stock injector rails and be able to get fed by the stock MAF and air box. the dual TB of andersons/Fan Threshy CF intake took quite a bit of set up to make work. but of course, it make big hp as well with little or now tuning.