sneax Posted June 15, 2017 Report Share Posted June 15, 2017 hey after my first topic here was answered fast and satisfying... I shoot my 2. question right away! :P for a rally race L20B engine - I want to put big valves in it, right? at least I got this impression, reading through the ratsun forum!I have no experience with building L engines what so ever. And the first reaction of my machine shop here in Mexico City was: "42mm intake valves? ...that should be big enough!" I am assuming they don't have a ton of experience with Datun L engines either! I am looking more for torque than high revs ...but 150 / 160 hp at the wheels would be great! I could use the 1000++ dollar for bigger valves very good on other parts for the racecar... but if that's what it takes to get sufficient power out off my engine.... I will spent them! 280z valves with 44mm\35mm in good quality?or can\should I go 1mm bigger to 45mm\36mm ???(price is the same for the 8 valves and for the job a well!!) Ferrea Competition Plus or any other recommendations? specs:L20B in an 1960 MGA for La Carrera Panamericana.W53 peanut headforged h beam rodsforged flat top pistons2x 45 webermaybe 270 or 280 camshaft for rally use. thanks guys :D Quote Link to comment
datzenmike Posted June 15, 2017 Report Share Posted June 15, 2017 What size valves are in the W53 head? Don't forget that larger valves will need the intake ports opened up to make use of them. Strength is built into the block, HP is made by the head... cam, valves, porting and polishing. More air flowing through the head, the more power made. Lots of things can be done to the head to improve the flow. The stock rods and pistons are good enough to 7K. Maybe add some ARP rod bolts. Keep it simple. To realize 150 hp you will need to really rev a 2 liter engine. I would shoot for 115/120. 1 Quote Link to comment
sneax Posted June 15, 2017 Author Report Share Posted June 15, 2017 I dont have the head here yet ... it is this one if that helps ?was advertised reasonly on the ratsun FB page! The H beam rods are 150mm long and give therefore a better rod\piston ratio as well... Intake and Ex port will be opened for sure!A bit revy is fine with me... the car is a pure street rally car! Quote Link to comment
datzenmike Posted June 16, 2017 Report Share Posted June 16, 2017 Right I remember now.... compression ratios. Just so you know, .... ratsun.facebook has less than zero connection the RATSUN.NET. 1 Quote Link to comment
wayno Posted June 16, 2017 Report Share Posted June 16, 2017 Them valves are big now, it looks like the seats are already touching each other. How big are the intake ports, normally the W53 has small runners but they can be larger, I have done it to a couple different heads. Quote Link to comment
sneax Posted June 16, 2017 Author Report Share Posted June 16, 2017 ok thank you - wayno! that would be great, if I have allready big valves in my head!here is a pic of the intakes: guess I will have to wait until I have the head in my fingers for more questions... :D 1 Quote Link to comment
wayno Posted June 16, 2017 Report Share Posted June 16, 2017 As I said, they look fairly big, but it is a photo, you will have to measure them when you get the head. The intake ports are small, you need to open them up so it can breathe, but it really depends on what intake system you are using. Quote Link to comment
flatcat19 Posted June 16, 2017 Report Share Posted June 16, 2017 I dont have the head here yet ... it is this one if that helps ? was advertised reasonly on the ratsun FB page! The H beam rods are 150mm long and give therefore a better rod\piston ratio as well... Intake and Ex port will be opened for sure! A bit revy is fine with me... the car is a pure street rally car! Grey Info lists L20B rods as 145.9mm. Which pistons are you using? Are you making a Z22 out of this? Quote Link to comment
sneax Posted June 16, 2017 Author Report Share Posted June 16, 2017 As I said, they look fairly big, but it is a photo, you will have to measure them when you get the head. The intake ports are small, you need to open them up so it can breathe, but it really depends on what intake system you are using. Ok ... will have to wait until I got it here! It will get fully ported - Intake and exhaust! Do you think 44mm 35mm is big enough for a rally engine? Grey Info lists L20B rods as 145.9mm. Which pistons are you using? Are you making a Z22 out of this? I searched and found H beam rods off the shelf!!! they have 150mm and match at the crank side 100%! will use custom flat top pistons! crank and stroke will be original L20B - I have to stay under 2000cc for the Carrera Panamericana! B) Quote Link to comment
Stoffregen Motorsports Posted June 16, 2017 Report Share Posted June 16, 2017 I would seriously consider building a long rod 2.0L for a rally motor. Search long rod here on Ratsun and see what you find. Quote Link to comment
wayno Posted June 16, 2017 Report Share Posted June 16, 2017 Ok ... will have to wait until I got it here! It will get fully ported - Intake and exhaust! Do you think 44mm 35mm is big enough for a rally engine? I have no idea. Quote Link to comment
datzenmike Posted June 16, 2017 Report Share Posted June 16, 2017 The Z20E used fattop pistons and 152.5" (6") rods and relatively cheap from a wrecker engine. Nothing custom needed, but maybe forged already exist for the Z20E? Look for '80-'82 HL510 or '80-'81 S110 200sx engines for them. Quote Link to comment
Stoffregen Motorsports Posted June 16, 2017 Report Share Posted June 16, 2017 The stock Z20E pistons have too high a compression ratio, when used with an L series head. And cutting them down enough to get anything around 10:1 results in cracked pistons. I built a few this way many years ago and all of the motors ended up with cracked pistons. But... Forged pistons aren't exactly expensive anymore. You can get a custom set now days for about $400, with pins and rings. And they will need to be custom to get the CR correct. If this is a race motor, I would run forged pistons anyway. 1 Quote Link to comment
wayno Posted June 16, 2017 Report Share Posted June 16, 2017 The stock Z20E pistons have too high a compression ratio, when used with an L series head. And cutting them down enough to get anything around 10:1 results in cracked pistons. I built a few this way many years ago and all of the motors ended up with cracked pistons. But... Forged pistons aren't exactly expensive anymore. You can get a custom set now days for about $400, with pins and rings. And they will need to be custom to get the CR correct. If this is a race motor, I would run forged pistons anyway. So even a open U67 L head will not work, too high CR? Quote Link to comment
datzenmike Posted June 16, 2017 Report Share Posted June 16, 2017 Z020E flattops and closed chamber A87 L series head and L20B crank is 10.69 compression. Above with open chamber (U67 / W58) head is 9.9 Quote Link to comment
MantisX620 Posted June 16, 2017 Report Share Posted June 16, 2017 But... Forged pistons aren't exactly expensive anymore. You can get a custom set now days for about $400, with pins and rings. And they will need to be custom to get the CR correct. If this is a race motor, I would run forged pistons anyway. I would like to know where? Quote Link to comment
flatcat19 Posted June 16, 2017 Report Share Posted June 16, 2017 Ok ... will have to wait until I got it here! It will get fully ported - Intake and exhaust! Do you think 44mm 35mm is big enough for a rally engine? I searched and found H beam rods off the shelf!!! they have 150mm and match at the crank side 100%! will use custom flat top pistons! crank and stroke will be original L20B - I have to stay under 2000cc for the Carrera Panamericana! B) Stroke is not original by using rods 5mm longer than original. Quote Link to comment
datzenmike Posted June 16, 2017 Report Share Posted June 16, 2017 Stroke is not affected by rod length. The Z20E has 152.5mm rods while the L20B has 145.9mm. Both run the came crank. Think about it. Quote Link to comment
Crashtd420 Posted June 16, 2017 Report Share Posted June 16, 2017 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.... Quote Link to comment
Crashtd420 Posted June 16, 2017 Report Share Posted June 16, 2017 Sneax how strict are the race rules... I came across this in my how to mod an lseries book.... Says an l20b with 86mm bore will be 2005cc displacement... I would hate to see them give you shit over 5cc.... And this is just my personal opinion... the w53 has 42mm and 35mm valves... I would think your money would be better spent porting and polishing and doing a cam upgrade over trying to get slightly bigger valves in there.... I hope you have a good budget.. I did alot of the same stuff on my l16 with a w53 head, and in the end it wasn't cheap.... I learned the hard way but very happy with the end result..... 1 Quote Link to comment
Crashtd420 Posted June 16, 2017 Report Share Posted June 16, 2017 Stroke is not affected by rod length. The Z20E has 152.5mm rods while the L20B has 145.9mm. Both run the came crank. Think about it. Is there any benefit to running a longer rod if the stoke is the same? Quote Link to comment
datzenmike Posted June 16, 2017 Report Share Posted June 16, 2017 Good Idea!!! I get 499.303cc per cylinder. This would make 1997.212cc total engine size with 86 bore and 86 stroke. This is the swept volume of the piston from BDC to TDC.... so I don't know what they are measuring. 1 Quote Link to comment
Crashtd420 Posted June 16, 2017 Report Share Posted June 16, 2017 Me either thats why i posted a pic of the book.. plus I'm the worst at those damn calculations... i used one of those online calculators and when I calculated mine it asked for dome or dished. I got the + & - Backwards.. . Oops... Quote Link to comment
flatcat19 Posted June 16, 2017 Report Share Posted June 16, 2017 Stroke is not affected by rod length. The Z20E has 152.5mm rods while the L20B has 145.9mm. Both run the came crank. Think about it. Not totally buying your theory. But... And...now the piston pin moves up...seems way too close to the top of the piston. Quote Link to comment
datzenmike Posted June 16, 2017 Report Share Posted June 16, 2017 86mm/10= 8.6cm x pi r2 = 58.0586 X stroke 8.6 (cm) = 499.303 (86mm must be divided by 10 to get into cm in order to get cubic cm) 1 Quote Link to comment
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