Dart B20+ Tall Block Question

[mr173]

Hi I was running a Dart B20+ tall block in NA set up.
Dart tall block is 14mm taller than stock B20 block

currently on (3.740")95mm storke with (5.967")151.5mm rods length.
For some reason I rebuilding it now and want to reduce the storke for (more higher rev thrills) and to get a better rod to stroke ratio (more efficient).

now planning to lower to (3.504") 89mm -stock B20 OR (3.433") 87.2mm -stock B18C stroke

I just want to confirm the following:

If I'm not wrong Egale rods catalogue shows that 89mm stroke also use 151.5mm rods for dart tall block

But what is the rods lenght for 87.2mm stroke? same 151.5mm?
:angel:
Thanks!!

[Benson]

Why not start with a b18c block and built from there? I would think it would make things easier

Ill go for the B20 block, they can handle up to 9400rpm on stock sleeves like ours.

[mr173]

Why not start with a b18c block and built from there? I would think it would make things easier

Ill go for the B20 block, they can handle up to 9400rpm on stock sleeves like ours.

Coz. I already have the dart tall block from few years ago and it has notthing wrong with it.

Moreover just thought if keep using a tall block running a 89mm or 87.2mm stroke can get a much better Rod/Stroke Ratio than B18 or B20 stock blcok set up.
The "Perfect" Rod/Stroke Ratio is 1.75 (if I'm not wrong)
Stock B20 Rod/Stroke Ratio 137mm/89mm =1.54
Dart B20+ Rod/Stroke Ratio 151.5mm/89mm = 1.70 (if I'm not wrong with the rod lenght)
Dart B20+ Rod/Stroke Ratio 151.5mm/87.5mm = 1.74 close to perfect (if I'm not wrong with the rod lenght)

So can anyone can clearify the rod lenght?
Thanks!

[Benson]

This is too technical

Might need to ask your engine builder

At the end of the day, you want to chase power... and its application of use

[ZeForce]

What is the compression height of the piston you plan to use?

[82911]

A quick look at the numbers you have supplied tells me that you have pistons with a comp height of 26mm.
Using your pistons..and a B20 (89mm) crank.
You will need 155.5mm rods.
This will yeild 13.5:1 comp,a displacement of 1972cc and a rod/stroke ratio of 1.75:1.

Using your pistons..and a B18C (87.2mm) crank.
You will need 155.5mm rods.
This will yield 11.8:1 comp, a displacement of1932cc and a rod/stroke ratio of1.78:1

Using your rods (151.5mm)..and a B20 (89mm) crank.
You will nee pistons with a comp height of 30mm.
This will yeild 13.5:1 comp, a displacement of 1972cc and a rod/stroke ratio of1.7:1.

Using your rods (151.5mm).. and a B18C (87.2mm) crank.
You will need pistons with a comp height of 30mm.
This will yield 12.7:1 comp, a displacement of1932cc and a rod/stroke ratio of 1.74:1.

You currently have.....
26mm comp height pistons (very light)
151.5mm rods
2105cc
rod/stroke ratio= 1.59:1.

Conclusion.............. you have a great combo of parts already, In your case I would not swap displacement for rod/stroke ratio.

[ZeForce]

A quick look at the numbers you have supplied tells me that you have pistons with a comp height of 26mm.
Using your pistons..and a B20 (89mm) crank.
You will need 155.5mm rods.
This will yeild 13.5:1 comp,a displacement of 1972cc and a rod/stroke ratio of 1.75:1.

Using your pistons..and a B18C (87.2mm) crank.
You will need 155.5mm rods.
This will yield 11.8:1 comp, a displacement of1932cc and a rod/stroke ratio of1.78:1

Using your rods (151.5mm)..and a B20 (89mm) crank.
You will nee pistons with a comp height of 30mm.
This will yeild 13.5:1 comp, a displacement of 1972cc and a rod/stroke ratio of1.7:1.

Using your rods (151.5mm).. and a B18C (87.2mm) crank.
You will need pistons with a comp height of 30mm.
This will yield 12.7:1 comp, a displacement of1932cc and a rod/stroke ratio of 1.74:1.

You currently have.....
26mm comp height pistons (very light)
151.5mm rods
2105cc
rod/stroke ratio= 1.59:1.

Conclusion.............. you have a great combo of parts already, In your case I would not swap displacement for rod/stroke ratio.

Couldnt have said it better myself....

[mr173]

Wow! So Accurate!
Yes, correct currently running on JE piston height is 26.54mm and bore is 85mm.
Thank you, I got my answer!
And reminded me to play around the engine displacement calculator again http://www.zealautowerks.com/
Thanks!

[82911]

50% of the stroke + rod length+ comp height of piston= total rotating assembly length.
Subtract that from the deck height gives you the piston to deck clearance.
But hey.. that online calculator is soooo easy!
How accurate is it in terms of comp ratio?

[B18cEG]

just to add, i am running a ERL performance raised deck and running 95mm stroke with 151.5mm rods, Just look at a stock b18c look how nicely they rev and to wat limit, with current setup rod/stroke ratio is almost exactly same as stock b18c, cant go wrong.

[moo moo nel]

Andy you been spending too much time on your engine :p

just sell it and buy a built B18C or B20B and start running with us :wave:

[mr173]

Hi Nelson! Now my engine rebuild is on the way, hopefully can join your guys on track again soon!! oh.. missing track day so much!!

Regarding the 95mm stroke engine set up, I agreed that it's already a great combo, it has notthing wrong it's just a little bit different "style" with 89mm stroke.

Since I was already running on 85mm bore/95mm stroke it's power curve not really making much power above 7500rpm, secondly with the long stroke the main concern is the relialbilty issue as the piston ring have to travel much further distance at very high rev. so when I with 95mm stroke the rev limit was limited at 8000rpm to be safe. If change to 89mm stroke "should" able to be worry free to set at 9000rpm or above! So it's just different "style" of setup!

Of course if there is notthing wrong I will not touch the current set up, but is just for some reason, I have to replace my internal anyway, it's boring to replace with the same set up, so I don't mind to testing on new rare setting to keep it interesting and share the result with your guys!!

Thanks for 82911, ZeForce and B18cEG advices! Especially 82911 have inspired me to use a "custom" 155mm rod lenght and I've learned "piston height".
Now my proposed setup is 85mm bore, 89mm storke, custom 155.5mm rod lenght, custom 26mm piston height therefore targeting 2020cc displacement, 1.75 r/s raito, 12.5CR

Will keep posted for new findings!

Cheers!

[82911]

FWIW...
Your new engine combination will make similar peak power,but slightly less torque than the current engine makes. This is provided you dont change the air flow path through the inlet or exhaust systems. This includes the cams.
What will happen though is this....
The longer rod and shorter stroke will move the power higher up in the rev range. You should gain some torque in the upper mid range because with the slightly longer rod the piston dwells at TDC longer.However, your overall torque will be lower.
The shorter stroke will drop your capacity, meaning that you have to rev the engine harder to move the same air through it and make the same peak power. This will shift your power curve upwards towards higher RPM 's. Making the engine more "peaky" than it is now.
All that will necesitate a change in gearing(shorter) to suit the peakier comination.
I think you have the best combination at the moment.I would leave it as is, and tune the power to the drivetrain ratios to gain the best performance for your chosen use of the vehicle.
To that end... What do you use the car for? Why do you want to rev to 8K + Rpm?
I believe their is a simpler answer, instead of re-inventing the wheel.

Regards Greg..

[ZeForce]

RPM = Ruins people's Motors

IMO if you can make the same power at a lower RPM then that's a better setup....

[fatboyz39]

Just add a blower to end of the motor. If your motor aint making power then go seek another builder/tuner. A 2.2L B series should make well over 160kw.

[Benson]

I think you are being tooooooooo creative. Just keep it simple and you'll make good power. There is heaps of info on honda-tech on simple combo's which makes great power.

All this custom rods and blah blah and making power here and there is all just too much.

But i guess you have too much money!

[Dart]

I am pretty sure there is a kit ( crank and rods )for the tall dart blocks might have been golden eagle check there web site..I was looking at that option ages ago but went another way

[mr173]

just to add, i am running a ERL performance raised deck and running 95mm stroke with 151.5mm rods, Just look at a stock b18c look how nicely they rev and to wat limit, with current setup rod/stroke ratio is almost exactly same as stock b18c, cant go wrong.

Hey B18cEG! You have experience on similar set upt, may I ask what size of bore you running at and what wkw your engine making now? just NA or Force Induction? :)

[B18cEG]

Hey B18cEG! You have experience on similar set upt, may I ask what size of bore you running at and what wkw your engine making now? just NA or Force Induction? :)

Motor is not together atm but i have the dart sleeves as well as the raised deck (ERL superdeck II) which pretty much makes it a closed deck. I am running 84mm bore with srp 13:1 and je file fit rings. estimated power output with all the parts i have is around 300hp at the flywheel. Buy we will have to see when its done.

[moo moo nel]

Hi Nelson! Now my engine rebuild is on the way, hopefully can join your guys on track again soon!! oh.. missing track day so much!!

WTF engine need rebuild already?
You only been to 2 or 3 track days with us :p

You not only got too much money
You are a super nice person too...hopefully this time THAT GUY is doing the job properly

[Slaz]

WTF engine need rebuild already?
You only been to 2 or 3 track days with us :p

You not only got too much money
You are a super nice person too...hopefully this time THAT GUY is doing the job properly

I'll comment here as im fit too, opposed to all the assumptions that are quick to appear on here Andy's engines failure was one many havnt seen before and no fault of the builder/tuner, rather the block manufacturer who have refused to come to the party with any help or compensation what so ever, so now what do you all suggest Andy or the engine builder do about that, take legal action against Dart..............? Goodluck! No one, not even Andy was aware the engine had a problem and it was driven for some time and hard when it should have been seen to, but when the driver/owner who doesnt have the greatest of mechanicial knowledge ( and no offence there Andy ) what is the builder to do when it turns up, what he can, strip it, find and explain the cause of what happened and fix it.

I to have fallen victim to a weird problem with my N/A engine where a sleeve had dropped .002 causing the head gasket to come away and pump water into the oil, what also happened is the sleeves became ovaled over only 20-30 hours running time causing the engine to lose comp, blow by was getting worse but how were we to know what the bores were doing, i had this block done in the us years ago and they have come to the party with it being sent back there for inspection and repair as they have stood behind there work, lucky me, it still cost me over 1k for shipping and then add to that, head service, gaskets, bearings, rings ect seeing you are there and it adds up, but it's at no fault of the builder but if it were out on a track the fingers would be pointed just like this.

Considering your talking about very stressed engines and the work they do, welcome to racing ladies, no warrenty and shit happens, parts fail as do people's budgets in keys areas or the ongoing care/servicing these built engines recieve once they go out the door.

Everyone is quick to point the finger without knowing shit or building an engine themselves, but you cant blame people for being upset when misfortune strikes them considering the money that gets spent on the toys we love, but this is life, get used to it or get out of the game, if Andy was upset or thought the engine had failed due to the builder, one would assume it would go elsewhere, Andy is a great guy who enjoys his hobbie and works his arse off to afford to have the car that he does yet people will carry on about him wasting it, who the f are you guys to comment on that?

Same shit different day, but it happens. my 2 cents. :thumbdwn:

[ZeForce]

I'll comment here as im fit too, opposed to all the assumptions that are quick to appear on here Andy's engines failure was one many havnt seen before and no fault of the builder/tuner, rather the block manufacturer who have refused to come to the party with any help or compensation what so ever, so now what do you all suggest Andy or the engine builder do about that, take legal action against Dart..............? Goodluck! No one, not even Andy was aware the engine had a problem and it was driven for some time and hard when it should have been seen to, but when the driver/owner who doesnt have the greatest of mechanicial knowledge ( and no offence there Andy ) what is the builder to do when it turns up, what he can, strip it, find and explain the cause of what happened and fix it.

I to have fallen victim to a weird problem with my N/A engine where a sleeve had dropped .002 causing the head gasket to come away and pump water into the oil, what also happened is the sleeves became ovaled over only 20-30 hours running time causing the engine to lose comp, blow by was getting worse but how were we to know what the bores were doing, i had this block done in the us years ago and they have come to the party with it being sent back there for inspection and repair as they have stood behind there work, lucky me, it still cost me over 1k for shipping and then add to that, head service, gaskets, bearings, rings ect seeing you are there and it adds up, but it's at no fault of the builder but if it were out on a track the fingers would be pointed just like this.

Considering your talking about very stressed engines and the work they do, welcome to racing ladies, no warrenty and shit happens, parts fail as do people's budgets in keys areas or the ongoing care/servicing these built engines recieve once they go out the door.

Everyone is quick to point the finger without knowing shit or building an engine themselves, but you cant blame people for being upset when misfortune strikes them considering the money that gets spent on the toys we love, but this is life, get used to it or get out of the game, if Andy was upset or thought the engine had failed due to the builder, one would assume it would go elsewhere, Andy is a great guy who enjoys his hobbie and works his arse off to afford to have the car that he does yet people will carry on about him wasting it, who the f are you guys to comment on that?

Same shit different day, but it happens. my 2 cents. :thumbdwn:

Not the first time I heard of issues with the dart blocks, but the same thing can happen with any sleeved block, there is always a chance they might sink.

http://www.theoldone.com/articles/Larryscivic/Larrys_Civic.htm

[Slaz]

Not the first time I heard of issues with the dart blocks, but the same thing can happen with any sleeved block, there is always a chance they might sink.

http://www.theoldone.com/articles/Larryscivic/Larrys_Civic.htm

Sure can and it a great read on how to do things right, but this very block failed very quickly aswell for those who care to read it, even after all that re working, so Larry must be a rubbish builder too? :rolleyes:

I was lucky the company that did mine stood behind the install and thats why i went to the effort of shipping it to the states as it was one of the 1st sleeved engines in the country and no one was really clued up on the install of them, a few machinist learnt alot of things by inspecting my block once it returned as i went and showed them as sleeve installs were becoming more popular.

These things just happen as can be seen in any motorsport right up to F1 and who can question the effort, parts, machinary and so on there?