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kota on 20s
GenIII
 
7/16/2002
19:48:36
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 Subject: RE: Twin-Turbo - R/T-2 is Alive!!
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some people use dished pistions (i thing) to lower the CR.
why do people lower the CR to add more boost? couldnt you get the same power out of a engine with highter CR and less boost? my question is what is the point?
Eric, 98 5.2 5speed, K&N gen II, 50mm TB, 2bbl M-1, 1.7RR's, JBA ciramic headers, carsound cat, dumped gibson, and a lot more
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Todd W
GenIII
7/16/2002
21:41:44
|  RE: Twin-Turbo - R/T-2 is Alive!!
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Probally the faster revving and the -supposed- greater torque. I don't know though, but I'm interested in finding out. Enough people I've talked to have suggested it that I'm curious about it. I've yet to decide if I'm going to overhaul my current engine as a S/Ced monster V6, or drop a V8 in and 'massage' it a bit... V6 sounds more fun to me, just because it's the road less travelled.
'00 RC Sport Forest Green, 3.9L, 5-speed 3.55, Hurst Comp-Plus Shifter, Clear-Corners, Speed-Glo gauges, Airaid Intake with relocated IAT, Autolite 3923s, Ported Throttle Body, Borg & Warner Cap/Rotor, Accel Coil, JBA 9mm Wires, JET Stage II, 185 T-stat, Flowmaster 40 w/dual out
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Brad
Dodge Dakota
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7/17/2002
08:41:44
| RE: Twin-Turbo - R/T-2 is Alive!!
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I think with the lower CR you have less chance for detonation. Although if you are throwing more boost at it I suppose the cylinder pressures could be the same as a higher CR lower boost combo. Maybe we will have to have tom or bernd explain this one.
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xplikt
Dodge Dakota
JOIN HERE
7/17/2002
09:15:17
| RE: Twin-Turbo - R/T-2 is Alive!!
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No, do not destroke a street engine; that doesn't make any sense to me, you'll loose a lot of your low end and grunt power where that long stroke makes the huge difference. If you're going to do anything to increase power, it would be stroking it and thus increasing the displacement of the engine.
kota, people lower the ratios so they can run more boost, but according to Corkey Bell, this will create a sort of sludge effect on the drivability of your vehicle. He reccomends keeping the ratio the same on a street engine or you're not designing the turbo system properly.
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POWER HUNGRY
Dodge Dakota
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7/23/2002
21:24:14
|  RE: Twin-Turbo - R/T-2 is Alive!!
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lowering the c.r. with different pistons allows you to run more boost because it is more detonation resistant. I think the lower c.r. allows more boost for an octance rating because it doesn't heat up the air/fuel charge as much threw lower mechanical work. Lower compression pistons also gives the turbo more volume to fill up(f.i. fills cylinder volume + combustion chamber volume-which you would be increasing).
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Torque_Less
Dodge Dakota
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7/23/2002
21:37:52
| RE: Twin-Turbo - R/T-2 is Alive!!
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When will this truck be done?
I heard that the owner of the TT R/Tis starting to get upset.
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sandman
Dodge Dakota
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7/23/2002
22:30:06
| RE: Twin-Turbo - R/T-2 is Alive!!
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xplikt, You are right that destrokeing is not the first thing to do it does have it's place and is not quite as evil as Corky Bell makes it out to be. I doubt that corky bell would ever belive that any idiot would ever be allowed to design pistons for an engine. If corky saw how close the rist pin and rings were to the top of the 4.7's pistons he would have a heart attack! You pretty much have to destrokit some for durability. I doubt that this engines current pistons would survive long at 14psi or higher. Think about it DC redesigned the pistons, rods,crank, heads and intake for their HO. This realy was not needed for 35 more HP. I am sure something else must be in the works. I am also woundering were one would get a stroker crank and rods custom made for $400.00 you can get custom made pistons for $400. in some cases. I doubt he is talking about alot of destroking. If you use a twin sequintial(sp) setup you can elimanate all sides of lag. I will add that a water or alchol to air intercooler can do wounders for a system. Water injection with boost controled timming also helps.
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sandman
Dodge Dakota
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7/23/2002
23:01:36
|  RE: Twin-Turbo - R/T-2 is Alive!!
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The Turbo Supra was the first car I ever lusted after. I still want one!!! The Lexus IS300 useing the same engine that the Supra used 3.0 I6 without boost. So you can imagine alot of people are basicly useing HIPO parts for the old Turbo Supra to build them up. The Supras start to leak oil out the rear main once you exceede 700HP-750HP. The top dogs in import raceing running Supra's are hitting 900-950 HP on rear real dyno. You can imagine that there is little left stock on these cars expect the block!!! If you want to understand why the Toyota engines (excludeing mid 90's 3.0V6 in trucks with bad head gaskets)just look at how heavy their engines are compared to competition of same displacment. A Toyota 22re 4 cylinder weights almost as much as a Chevy small block, Their V6 weight about the same as small block and the I6 weights more then a small block. The reason for the weight it because they make the walls thick. The less your block flex's at the base the better the parts fit and wear. Block flex is bad and a flexing block will mean a flexing crank witch is even worse. DC did an excellent Job on the new 4.7. The only thing that must go is the realy bad bad bad pistons. The HO is even closer to perfect. I can almost gurantee that all of us with 4.7L engines will be useing alot of oil at 150,000 mile. Toyota is bringing back the Toyota Supra I read this in Car and Driver or Moter Trend. I doubt that it will be Turbo charged. It will probably have a V8. I am hopeing for a HiPo Lexus V8 or the new 5.4 Truck V8 they are working on. Either way you can rest assured it will be a real sports car!!!!!! Now if Dodge would just build me a Mid Engine rear wheel drive sports car the size of a Neon with the HO 4.7 super charged at 8psi with a 5-6 speed manual trans for about $25,000 I would get in line to place an order for one!!!!!
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xplikt
Dodge Dakota
JOIN HERE
7/24/2002
00:06:30
| RE: Twin-Turbo - R/T-2 is Alive!!
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sandman, that is a very nice dream you have there, but you'll be waiting in line behind me for that one ;)
sandman, Corkey Bell has never mentioned anything about destroking an engine, that was all my interpretation from mechanics/car builders I've talked to and books I've read. The part I was talking about Corkey Bell was the compression ratios. I just don't know why you want to move the power band higher up for street use. Maybe if you started with a larger, mucho low end torque) engine to begin with, but not the 4.7.
I would say stroke the 4.7L, I know there's room, but you would destory the engine if you reved to high (or you could just NOT rev it so high) with many stock parts and I think it would rip the NV3500 in two. A stroked 4.7L would produce more power than a stock 5.9, but why didn't they put the 5.9 in with the 5-spd again...
Agreed, the 4.7L does not some serious engine strengthening..
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Bernd
*GenIII*
7/24/2002
21:10:27
| RE: Twin-Turbo - R/T-2 is Alive!!
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He's not getting upset...just ansy (or however you spell that). Maxx (owner of R/T-2) is coming down to the shop on Friday to help with the final installation (tubes are coated and on their way back to us). Once this is done...we "should" be able to get down to the Dyno shop and tune the (very adjustable) FMU for proper A/F ratio at all boost ranges.
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
14.55 @ 96.01mph
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sandman
Dodge Dakota
JOIN HERE
7/24/2002
21:31:44
|  RE: Twin-Turbo - R/T-2 is Alive!!
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Hey I agree more cubic inch's are always better then fewer for low end torque. The reason for the mild and I mean mild destroke of the 4.7 would be to redsign the pistons for heavier usage. The factory design is seriously flawed and would not take alot of boost for very long before a catotrophic failure occured. The next reason is bore to stroke ratio. Long rods are good because they increase dwell at TDC but that does little good is the bore is such that you get exxagerated piston slap or extreme rod angles at the moment of combustion. You are also limited by how much material you can remove from the block to clearance those rods. Harmonics are also important. The 4.7 can probably be made into a 5.2 or 5.3 and that is about it. They did nt leave alot of room for growth. It would be easier for them to add two more cylinders to make a modern 10 cylinder. Hope this all sounds ok. I have not had much sleep in the last 48 hours so my brain is not running on all cylinders right now!!!!
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Duner
Dodge Dakota
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7/25/2002
18:11:42
| Slightly shorter rod...
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All the 4.7 engine needs is a rod that's about
.10" shorter and add that distance to the
ring-land area at the top of the piston..... and
make them forged pistons. The bore and stroke are
fine the way they are. Other than the pistons - I
think the 4.7 engine will prove to be plenty
strong enough.
DC is already planning a 10 cylinder engine based
on the 4.7's design.
http://www.allpar.com/mopar/
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