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L18 vs (L)z20


gumby510

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Ok, datzenmike has me thinking.

I have my z20e motor on the way, which has the desirable 6in rods.

Now im thinking of doing 2 motor builds now.

Build my current L18 and use the forged 87mm pistons I have.
And
Do the z20e with a a87 peanut head and some 87 or 88 mm pistons.

So my question is using the same head (built a87 peanut), cam, solex 40mm (36mm venturi) twin side drafts, header, exhaust (2.25in)and compression ratio (10:1cr for comparison.)

L18 -1854cc
Vs
LZ20e-2045cc

1. How would these motors compare to each other in terms of hp/tq and "enjoyment" of the driving experience. This is not a track car.

2. Is it as simple as the Lz20e will have 10% more hp and tq over the L18 along with having a lower power band.?

3.Is using my twin solex 40mm side drafts going to choke or limit the performance of the z20?

4. Between the 2 is/would there be a night and day difference? Or would it be more of a subtle difference.

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In my experience, the long rod Z20 with an L head was so much fun to drive. Any stock L motor didn't have the smooth torque that the long rod motor delivers, and the rev capabilities were much greater too. I don't have actual horsepower numbers in a direct comparison, but you could really smoke the tires with a long rod 2.0L.

 

One caveat is the pistons. The stock pistons can be cut to lower the compression, but then they are so thin that they will probably crack (I've made this mistake a couple times). so if you're buying custom pistons, why not just bore it to 89mm and have a long rod 2200, which is a much better motor. You can easily make 150hp with a down draft Weber or 210hp with dual 44's, with pump gas and 10:1. So in a nutshell, spend the extra couple hundred bucks and have it bored for 89mm and be much happier with the money you've spent.

 

Night and day? I would say yes. The strongest L18 I ever had was fun, but just enough fun. The long rod 2.0 was able to get me into trouble.

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Thank you for the response, I would more than likely have custom pistons made for the z20. The only thing im really worried about with that setup is/would be if my 40mm solex carbs would choke power. They are the solex addhe 40mm with 36mm venturi, these are off of a alfa gtv. There supposed to flow more than the phh and are lighter. Mine are also connected to the long tube cannon manifold.

 

Im trying to judge how much more money to spend on my L18. Im not chasing big power or anything im just looking to make my 510 more fun.

 

 

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the Jap carbs are better!!!!!adde are the italian carbs. dont know much about them.

40mm would be good for the all aroundstreet driving

I would do L20 if I had to do it all over again but stuck with l16/18s

 

I had a L20 510 and the fucker pulled hard . Nothing fancny . Good Cam and head was the most likely the key. it only had 240mm mikunis and was a dailly driver. run on super91. No issues

Edited by banzai510(hainz)
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5 hours ago, banzai510(hainz) said:

the Jap carbs are better!!!!!adde are the italian carbs. dont know much about them.

40mm would be good for the all around street driving

I would do L20 if I had to do it all over again but stuck with l16/18s

 

I had a L20 510 and the fucker pulled hard . Nothing fancny . Good Cam and head was the most likely the key. it only had 240mm mikunis and was a dailly driver. run on super91. No issues

 

Thats what I have heard but that typically from people who have only run phh. So I dont know if theres a difference in build quality? From all the things I read the addhe are lighter, flow better and are/were more reliable? I bought the clean pair of 40mm addhe for $250 so I couldnt really pass them up.

 

Gas wise ill be running 93oct

 

It seems overwhelming in favor of the 2.1L. So I think Ill run the L18 with the 87mm pistons for a year or 2 wile I build up the z20 block.

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I sold me 40 ADDE for 150 with a cannon manifold. They were so old and I didnt want to fuck with them. But really looked good. I hear there rebuilt kits on ebay or amazon somewhere.  Back in the day they were sold to Datsun guys but had the 2 pc manifold  one for each carb which I think is stupid.  I like bol the whole thing as once and hook up the cable

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18 hours ago, Stoffregen Motorsports said:

I used them and ebay for the rebuild parts. The gasket kit on ebay was only $15ea.

 

With the long tube cannon manifold I dont think ill be able to use the center pull without hitting the hood so im going to try a single side weber cable linkage.

https://www.ebay.com/itm/293676763870

 

Now that I think about it I can probably just flip flop the center linkage and it would probably work..... I feel dumb now.

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1 hour ago, banzai510(hainz) said:

I thought the ADDE was Italian solexes?

 

my cable come from the side

engine_4.jpg

 

You are correct that they are italian solex's. Maybe im incorrect with my understanding but arent those considered center pull (throttle actuation between the 2 separate carb bodies)? Looking at the pic on my phone maybe im just not seeing it clearly.

I take some pics of mine and post them up.

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Centerpull is where the two carbs are connected in between the two carbs, not with individual linkage rods. The centerpull kit I saw on that website used the rod above to actuate the centerpull, but could easily be modified to use a cable instead.

 

ADDE? You mean ADDHE. Yes, they are Italian and found mainly on Alfas. They had a funny jet cover with multiple screws holding it on, not one in the middle, like a PHH. I've had a few pairs of them, but never run them.

 

Solex's get even weirder. Some of the really old ones found on MBZ had another set of butterflies up front as the choke.

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2 hours ago, Stoffregen Motorsports said:

Centerpull is where the two carbs are connected in between the two carbs, not with individual linkage rods. The centerpull kit I saw on that website used the rod above to actuate the centerpull, but could easily be modified to use a cable instead.

 

ADDE? You mean ADDHE. Yes, they are Italian and found mainly on Alfas. They had a funny jet cover with multiple screws holding it on, not one in the middle, like a PHH. I've had a few pairs of them, but never run them.

 

Solex's get even weirder. Some of the really old ones found on MBZ had another set of butterflies up front as the choke.

Yes, I ment addhe.

This is what I have, correct me if im wrong but id consider this center pull.

20210304-181540-2.jpg

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