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I want bigger valves for this setup, right?


sneax

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Not totally buying your theory. But...

 

 

And...now the piston pin moves up...seems way too close to the top of the piston.

 

Stroke is only a function to the stroke of the crank X 2. An L20B crank has a rod offset from the centerline by 43mm but when turned travels through 86mm top to bottom. The rod, even if a mlile long can only move 86mm.

 

Yes the piston pin has to move higher in the piston to allow for a longer rod to prevent it popping out of the bore. Some race pistons have plugs for the pin hole and a slot for the lower ring.

 

The L series pin height is 38.1mm the Z20E piston is 31.75 or about 6.35mm close to the same fifference between the two rods used. 152.5mm - 145.9mm = 6.6mm 

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The irony is I was that guy at school that said who the hell needs math.... and here we are using it... damn it....

 

Totally!!!!

 

I have used more math (hopefully correct) hear than at any other time.

 

Again if anyone disputes my numbers I have no problem correcting it if wrong. Easy enough to assume something and go off on a tangent. I'd rather have something right here. Barely passed mathe at school... if only they had used a compression ratio as an example...

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this build is not about getting cheap parts!
It is about getting torque and HP on the street!!!
Yes - there is a budget... but if I have to spend 5-6 Grand.... I will!
But therefor I want decent power and good quality!
 

@Cashtd: yes there i a benefit of longer rods... Look up rod to stroke ratio!
and if I get forged H beam rod for 270 dollar us... why not!!!

 

 

maybe I should ask different:
Does anyone have examples of an L20B high power engine with the original 42mm / 35mm  valves???
My guess is they will be all under let say 140HP at the wheels...
Anyone? 
:D

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I would like to know where?

 

 

Ya I was gonna say....

Maybe if they are in production... custom will probably double that cost.. plus if your going with flat tips you need 2 different piston because of the valve relief ... left and right hand....

 

Call around. JE, Wiseco, etc all have "custom" pistons already designed and ready to cut. Since this is not a crazy new engine combo, the designs are pretty standard.

 

I admit, I was exaggerating a bit, but they aren't going to be much more than $400 or $500 per set. When talking about a performance racing type engine, this is not a ton of money.

 

And you can save money by cutting your own reliefs. I would do that anyway as you never know what you need until you mock it up with the cam you're going to use.

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Stoffregen Motorsports, on 16 Jun 2017 - 7:32 PM, said:

 

Call around. JE, Wiseco, etc all have "custom" pistons already designed and ready to cut. Since this is not a crazy new engine combo, the designs are pretty standard.

 

I admit, I was exaggerating a bit, but they aren't going to be much more than $400 or $500 per set. When talking about a performance racing type engine, this is not a ton of money.

 

And you can save money by cutting your own reliefs. I would do that anyway as you never know what you need until you mock it up with the cam you're going to use.

 

Yeah ... they are affordable these days! 400 is a bit lowballed ... I will get Venolias for about 110 dollar each without rings... all other are about 200 each!

forged from the shelf are available for 4-500 dollar a set of 4!

 

BUT: do I need big valves??? ;)

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Yes, you need big valves.

 

I don't know, sheesh...

 

What do your rules allow? How much HP are you trying to make? What induction? What's your budget?

 

do I need bigger valves to get over 140RWHP ...would have been a more understandable question to ask I guess!  :thumbup:

 

Rules are only limiting to max 2000cc, 8valves, natural aspirated, wet sump.... 

 

Trying to make as much Torque as possible... to beat all the porsches 356 in my class   :thumbup:

 

budget for the engine build.... hmmm maybe 5-6 grand

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A W53 head already has the largest valves that were available in a Datsun L4, but if you're porting the head anyway, bigger valves (and the work that goes along with them) isn't going to break the bank.

 

For 140 HP at the wheels, yes, you're right on the bubble.

 

Are you going to build this motor yourself?

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this build is not about getting cheap parts!

It is about getting torque and HP on the street!!!

Yes - there is a budget... but if I have to spend 5-6 Grand.... I will!

But therefor I want decent power and good quality!

 

@Cashtd: yes there i a benefit of longer rods... Look up rod to stroke ratio!

and if I get forged H beam rod for 270 dollar us... why not!!!

 

 

maybe I should ask different:

Does anyone have examples of an L20B high power engine with the original 42mm / 35mm  valves???

My guess is they will be all under let say 140HP at the wheels...

Anyone? 

:D

 

Too much time is spent on rod stroke ratios. Don't read too much into those discussions. It's mostly geometry and esoteric theory with little real world examples. So as long as the ratios are reasonably in range the gains (if any) aren't worth the bother except to racing teams with the equipment and money to exploit it. You want something you can throw together and make power.

 

.    

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A W53 head already has the largest valves that were available in a Datsun L4, but if you're porting the head anyway, bigger valves (and the work that goes along with them) isn't going to break the bank.

 

For 140 HP at the wheels, yes, you're right on the bubble.

 

Are you going to build this motor yourself?

 

 

I have help by a good race engine machine shop and a bunch of race mechanics. BUT - they work mostly on VW and big V8 engines ... never on L20Bs!!! They have build the engines of the first 6 places of last years Carrera Panamericana (all >700RWHP studebakers) and a lot more... 

 

​so we all have a general understanding of building old performance engines ... but non of us touched an L20B! 

And I think/know now that there are quite some specialities of the L20B to understand to get it over those 130-140 RWHP!!! 

 

 

spend money on head and cam. Carbs

 and maybe ARP bolts

 

your weal link is worn out distributor. try t o get most power by 6500 is my opinion and maybe a low ratio limited slip diff

 

 

Mexico has crappy gas anyways why worry about fancy pistons.

We will have to use that crappy gas by the rules and ad Octainbooster!

 

What distributor or ignition system would you recon? one of those electronic distributors like this one?

 

s-l1600.jpg

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Use a single point factory distributor.  That's what I'll be using at Bonneville in August with a similar engine build.  86.5 mm bore, 2 liter.  The matchbox has issues at higher rpms.  Timing regression mostly, so loss of power.  My single point is set up to run over 9000 rpms with no loss in timing or signal quality.  Yours only needs to last a week, so worrying about points wear/failure is silly, and as small as the cylinders are, don't complicate it with MSD or other crap that may leave you stranded.  

 

Stay away from the "new" stuff, unless its a legit NOS Hitachi.  Made in China $11 reproduction distributors are worth the $11 that they sell for wholesale.  

 

Maybe call Rebello and see what pistons he might have available for your build.  JE pistons are much less expensive when you repeatedly make the same ones over and over.  He just has to call in an order number to reproduce a known good piston formula with great piston-to-valve clearances and the right compression heights.  He'll also tell you who to get your rods from.  Then again, maybe you want to have him just put the motor together for you? 

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I went through some of this recently in my engine rebuild. I took an l20b that was bored 30 over. then took my open chamber a87 head, had 1mm larger intake valves (280zx?) installed. did a bowl blend, and a mild port, also installed new springs and retainers all the way through, came out really nice, however, I have a stock cam still, and running a 38/38 webber. I think I could really use a good cam in there to take advantage of the headwork. I say go for it, just as others have said, headwork is where you'll gain the air flow. which helps big time.

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I have help by a good race engine machine shop and a bunch of race mechanics. BUT - they work mostly on VW and big V8 engines ... never on L20Bs!!! They have build the engines of the first 6 places of last years Carrera Panamericana (all >700RWHP studebakers) and a lot more... 

 

​so we all have a general understanding of building old performance engines ... but non of us touched an L20B! 

And I think/know now that there are quite some specialities of the L20B to understand to get it over those 130-140 RWHP!!! 

 

 

What distributor or ignition system would you recon? one of those electronic distributors like this one?

 

 

For 140 at the wheels, you'll need roughly 170 at the crank, which is totally doable with a L20B. But the race you are competing in is a long, sustained mid to high RPM fest and I would not scrimp on the rotating assembly. Money spent there will ensure a level of reliability that you need for endurance racing.

 

Assuming you have a good machine shop that knows how to polish a crank and size the rod/main bores, balance the assembly, etc, there are still a couple tricks you should employ.

  • Use tri-metal bearings with a full groove (upper and lower shells), Clevite has sold NDG stamped bearings in the past, which are basically OEM.
  • Drill the #2 and #4 oil feed holes (in the block to the main bearings) to 1/4".
  • Be sure to drill the corresponding main bearings too.
  • Chamfer all oiling holes in the crank before polishing.
  • Do a good block prep including stress relief stuff like chamfering and de-burring.
  • Assuming you are going to use OEM rods (either N85 or U60 castings), have good ARP bolts installed before re-sizing.
  • Use new main cap bolts or studs. Grade 10.9 socket head cap screws are fine.
  • I wouldn't worry about trying to shave weight from the rotating assembly. Knife edged crank or super light flywheel are good for road racing, but you won't need these. Just run a stock, lightened flywheel to save those pounds.

Horsepower will come from the top end, and valvetrain stability should be a concern. Some of the "off the shelf" racing cams are antiquated and hard on valvetrains, so buy a cam with a modern grind to help keep things in place. I might consider having a Datsun pro build the head. You can expect to spend about $1500 to $3000 for a race head. The $1500 head should be enough for your HP requirements.

These tricks have been around for decades and

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Use a single point factory distributor.  That's what I'll be using at Bonneville in August with a similar engine build.  86.5 mm bore, 2 liter.  The matchbox has issues at higher rpms.  Timing regression mostly, so loss of power.  My single point is set up to run over 9000 rpms with no loss in timing or signal quality.  Yours only needs to last a week, so worrying about points wear/failure is silly, and as small as the cylinders are, don't complicate it with MSD or other crap that may leave you stranded.  

 

Stay away from the "new" stuff, unless its a legit NOS Hitachi.  Made in China $11 reproduction distributors are worth the $11 that they sell for wholesale.  

 

Maybe call Rebello and see what pistons he might have available for your build.  JE pistons are much less expensive when you repeatedly make the same ones over and over.  He just has to call in an order number to reproduce a known good piston formula with great piston-to-valve clearances and the right compression heights.  He'll also tell you who to get your rods from.  Then again, maybe you want to have him just put the motor together for you? 

Ahh - good stuff! 

KISS = keep it simple, stupid!

The original distributor I can buy at my local Nissan/Datsun dealer, right?

I will give Rebello a call tomorrow - maybe they got some pistons for me .... although I am using different rods and therefor a different pin height!

 

What are you racing for in Bonneville? wanna break some old records?

Can you give me some details of your engine build? or witch topic can I read here for your build?  :thumbup:  

 

 

 

For 140 at the wheels, you'll need roughly 170 at the crank, which is totally doable with a L20B. But the race you are competing in is a long, sustained mid to high RPM fest and I would not scrimp on the rotating assembly. Money spent there will ensure a level of reliability that you need for endurance racing.

 

Assuming you have a good machine shop that knows how to polish a crank and size the rod/main bores, balance the assembly, etc, there are still a couple tricks you should employ.

  • Use tri-metal bearings with a full groove (upper and lower shells), Clevite has sold NDG stamped bearings in the past, which are basically OEM.
  • Drill the #2 and #4 oil feed holes (in the block to the main bearings) to 1/4".
  • Be sure to drill the corresponding main bearings too.
  • Chamfer all oiling holes in the crank before polishing.
  • Do a good block prep including stress relief stuff like chamfering and de-burring.
  • Assuming you are going to use OEM rods (either N85 or U60 castings), have good ARP bolts installed before re-sizing.
  • Use new main cap bolts or studs. Grade 10.9 socket head cap screws are fine.
  • I wouldn't worry about trying to shave weight from the rotating assembly. Knife edged crank or super light flywheel are good for road racing, but you won't need these. Just run a stock, lightened flywheel to save those pounds.

Horsepower will come from the top end, and valvetrain stability should be a concern. Some of the "off the shelf" racing cams are antiquated and hard on valvetrains, so buy a cam with a modern grind to help keep things in place. I might consider having a Datsun pro build the head. You can expect to spend about $1500 to $3000 for a race head. The $1500 head should be enough for your HP requirements.

These tricks have been around for decades and

Wow - that great information that I did not know yet!!!

 

The Clevite NDG bearings are the one I wanna use, right?

What is meant by de-burring?

For the flywheel I read about the aluminium 280z flywheels... or can I machine down my original one?

Lighter balancer as well? can I machine it as well?

(Machine work is cheap here in Mexico! way cheaper than buy new part from the Usa!  :thumbup: )

And for that reason I will have intake and a full length exhaust custom build here for me a well!

 

I will use these rods:

http://www.ebay.com/itm/172647155458?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

they fit, are strong, cheap, come with ARP bolts, and give me a better rod\stroke ratio as well!

they have a 23mm pin - no problem as I am going to use custom (Venolia if not Rebello) pistons for it!

the pistons will have 86mm for real 2 liter, a compression height of 34.85 and 5cc pockets!

(the pin height is 34.85 to have a squish of 0.8mm, and the 5cc pocket to adjust the c/r to ~10.6:1 ... as mentioned earlier!

How deep the pockets will get, was a question from Venolia for the thickness of the top of the pistons - but I think I solved it mathematically  = ~6mm)

 

 

 

 

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The U60 rods are 5.85" and the N85 rods are 6". Most off the shelf custom pistons are made for these two rod lengths. If you're going out on your own and using a 5.9" rod, you may be paying custom piston price, but then the saving on the rods (these are very cheap) will more than cover it.

 

I've always wanted a MGA coupe, to build just as Huffaker built them back in the day. There is a particular green one that looks soooooo sexy.

 

Your car is very cool too.

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The U60 rods are 5.85" and the N85 rods are 6". Most off the shelf custom pistons are made for these two rod lengths. If you're going out on your own and using a 5.9" rod, you may be paying custom piston price, but then the saving on the rods (these are very cheap) will more than cover it.

 

I've always wanted a MGA coupe, to build just as Huffaker built them back in the day. There is a particular green one that looks soooooo sexy.

 

Your car is very cool too.

 

OK - I did not know about the pistons for those rods! are they forged? for different compression rates or deck heights available?

can you give me a link where to find them?

 

And are the U60 and N85 rods strong enough... and light as well? I only red about the Z20 in long rods! Are they the same?

 

thanks for your help again!  :thumbup:

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