2.7 litre potential vs. 2.8 litre potential
01-30-2008 | 01:40 PM
#16
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How does the unreliability manifest itself on some of these larger motors? What has been the quantifiable faults of boring? Weaker cylinders, therefore movement/leakage? There are ways of preventing that. What else?
01-30-2008 | 01:44 PM
#17
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I agree, wide pistons too, but the torque would be huge.
On the other hand, the flame travels across these chambers alot quiker with a good charge than a BUNCH of timing tuners would think.
Don't believe that there is zero space between peak power advance and engine damage.
That is NOT the case.
On the other hand, the flame travels across these chambers alot quiker with a good charge than a BUNCH of timing tuners would think.
Don't believe that there is zero space between peak power advance and engine damage.
That is NOT the case.
01-30-2008 | 02:39 PM
#18
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Ehall,
If it boils down to saving the $1-1500 on the crank, I would suggest you take that money and invest it into a well built 2.5ltr motor.
I would be concerned with build quality and an over all system, ie TB, intake, head etc..
If it boils down to saving the $1-1500 on the crank, I would suggest you take that money and invest it into a well built 2.5ltr motor.
I would be concerned with build quality and an over all system, ie TB, intake, head etc..
01-30-2008 | 03:21 PM
#19
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To do that I'd need a 3.0 block, but I only have a 2.5 block.
01-30-2008 | 03:32 PM
#20
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From: Firestone, Colorado
Not sure if this was discussed here: is the rod to stroke ratio and piston speed.
Just doing a stroker using the same length rods will add increased piston side load and also increased piston speed. The results are generally increased piston wear also the top end rpms are being shorted for the lack of dwell time for a more efficient burn rate .
To me it would be a matter of where you plan on spending the majority of your time. If it were at the track at 5000+ rpms I would go larger bore but if a street driven vehicle the torque would be my choice hence the stroker. Now if you can run longer rods and achieve the same rod stroke ratio then either is good IMO.
Just doing a stroker using the same length rods will add increased piston side load and also increased piston speed. The results are generally increased piston wear also the top end rpms are being shorted for the lack of dwell time for a more efficient burn rate .
To me it would be a matter of where you plan on spending the majority of your time. If it were at the track at 5000+ rpms I would go larger bore but if a street driven vehicle the torque would be my choice hence the stroker. Now if you can run longer rods and achieve the same rod stroke ratio then either is good IMO.
01-30-2008 | 03:33 PM
#21
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01-30-2008 | 03:40 PM
#22
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Thanks for the input thus far. The reason I brought this up is that I'm interested in potentially improving the torque off boost. This will be a strictly road car project, so I'm after torque in the lower rev ranges rather than massive hp.
I'm concerned that evewn a really well built 2.5 will still not improve the off boost torque very much. Will the larger TB, head work and intake really change that handicap? It seems like all of the intake manifolds that I see fail to do much for increased torque?
Where is my thinking off on these points?
I'm concerned that evewn a really well built 2.5 will still not improve the off boost torque very much. Will the larger TB, head work and intake really change that handicap? It seems like all of the intake manifolds that I see fail to do much for increased torque?
Where is my thinking off on these points?
01-30-2008 | 03:42 PM
#23
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01-30-2008 | 03:46 PM
#24
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From: Firestone, Colorado
Thanks for the input thus far. The reason I brought this up is that I'm interested in potentially improving the torque off boost. This will be a strictly road car project, so I'm after torque in the lower rev ranges rather than massive hp.
I'm concerned that evewn a really well built 2.5 will still not improve the off boost torque very much. Will the larger TB, head work and intake really change that handicap? It seems like all of the intake manifolds that I see fail to do much for increased torque?
Where is my thinking off on these points?
I'm concerned that evewn a really well built 2.5 will still not improve the off boost torque very much. Will the larger TB, head work and intake really change that handicap? It seems like all of the intake manifolds that I see fail to do much for increased torque?
Where is my thinking off on these points?
You actually answered your own question here as the only way to make significant gains in power off boost using such a low CR is the crank length. Everything else is to create a better VE at higher RPMS.
01-30-2008 | 04:52 PM
#25
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My setup for a brief time was a 3.0L w large cam, racehead, modified inlet, larger t/b, Stage 5 turbo. Now I was just running the motor in so not getting on any real boost nor high rpms. The extra CC's took care of everything low down and the few times I gave it a little squirt, all the rest took over. You could even go a step further as I have and change out your 951 cw&p to a S2 cw&p which shortens your final drive quite a lot. This also really helps in off boost. Be prepared to sacrifice ultimate top speed (how fast do you need to go?) and changing gears a little faster or earlier. A worthwhile mod in my books.
However, I can really extol the virtues of the 3.0L and I wouldn't go back to anything smaller again. Might go larger of course...
Once you're sleeving and buy a 3.0L crank it is crazy not to in my book.
However, I can really extol the virtues of the 3.0L and I wouldn't go back to anything smaller again. Might go larger of course...
Once you're sleeving and buy a 3.0L crank it is crazy not to in my book.
01-30-2008 | 06:03 PM
#26
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That's a pretty good point about going 3.0. I actually investigated all of this back in 2003, and did some real homework, but a number of things have changed over the last five years.
Now that I have most of the cash on hand, it's back to the books. The options for larger displacement builds have become MUCH better.
BTW, I got your pm patrick. I'll reply later on. Thanks.
Now that I have most of the cash on hand, it's back to the books. The options for larger displacement builds have become MUCH better.
BTW, I got your pm patrick. I'll reply later on. Thanks.
01-30-2008 | 06:04 PM
#27
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I have not seen any results from a 2.7L (104mm), so I cannot comment on it.
I have experienced, owned or tuned the 2.5L, 2.8L (106mm), 2.8L (Stroker 100mm, 3L crank) and 3.0L (104mm, 3L crank).
If a engine rebuild is required where sleeving is a must, the 2.8L is the best bang for the $. It performs great, lives a long time when built and setup correctly.
It all boils down to your budget, where you want your powerband to be, street only or street/track.. Turbo selection, tuning, etc.. are all factors that will play a huge role in the success of your project.
ehall, I assume you are working with a engine builder. It's a good idea to ask for a dyno chart or get a ride with someone that has a particular engine you are looking for. At least you will get a idea of the "feel" of the car. As far as reliability, discuss it with the customers. If you want to view a few dyno charts, comparing a 2.5L, 2.8L (big bore) and a 3L, drop me a email, we can take it off-line.
I have experienced, owned or tuned the 2.5L, 2.8L (106mm), 2.8L (Stroker 100mm, 3L crank) and 3.0L (104mm, 3L crank).
If a engine rebuild is required where sleeving is a must, the 2.8L is the best bang for the $. It performs great, lives a long time when built and setup correctly.
It all boils down to your budget, where you want your powerband to be, street only or street/track.. Turbo selection, tuning, etc.. are all factors that will play a huge role in the success of your project.
ehall, I assume you are working with a engine builder. It's a good idea to ask for a dyno chart or get a ride with someone that has a particular engine you are looking for. At least you will get a idea of the "feel" of the car. As far as reliability, discuss it with the customers. If you want to view a few dyno charts, comparing a 2.5L, 2.8L (big bore) and a 3L, drop me a email, we can take it off-line.
I'll email you later on tonight.
E
01-30-2008 | 07:16 PM
#28
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I have a slightly OT question, does Darton make sleeves with a larger than 78.9mm bore that fit the 2.5 block?
And also, how much does that deck plate cost? I heard "expensive" but that could mean anywhere from $800 to $3500 in my book.
And also, how much does that deck plate cost? I heard "expensive" but that could mean anywhere from $800 to $3500 in my book.
01-30-2008 | 07:24 PM
#29
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M.I.D. sleeves go to 104 mm in a 2.5 block. For larger you need a 3.0 block. Then you can go to 106mm.
I think you might have misplaced the 78.9mm for bore rather than crank. For deck plate info, you'll need to pm evil 944t. I wouldn't presume to speak for him.
I think you might have misplaced the 78.9mm for bore rather than crank. For deck plate info, you'll need to pm evil 944t. I wouldn't presume to speak for him.