1900 build

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merlinvenn27
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1900 build

Post by merlinvenn27 »

Sup guys. Recently converted my car to 2lt. I've got a complete AFX engine to mess around with. Here's my plans: send the head in for stage 2 headwork at 8v performance, run a 276 or 282 cam. Bottom end I want the magical 1900 setup I hear about. However I am at a bit of a cross road when it comes to the correct pistons. I already know you have to change the crank (1.8). Pistons I'm a bit confused about;I know that they have to 40thou oversized (83.5mm). The 2.3 caravelle pistons require about 1.5mm being shaved off from the crown (Im not too fond of that idea) then the 2.5 pistons require the block to be decked(about the same iicr). From a reliability point, which would be the safer option? All opinions and advice would be appreciated. Thanks guys
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Re: 1900 build

Post by panic-mechanic »

2.5's and shave the block
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Re: 1900 build

Post by merlinvenn27 »

Perfect. Im going to chat with the engineer at R&B in Pine Town one of the days, when it comes to the engineering, how far must must the piston 'stick' out of the block? I don't want to spend money and find out that the compression isn't right or the car is pinging lie crazy. I want to do this once and correct the first time.
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Re: 1900 build

Post by missioner »

Use an 86.4mm crank from a 1.8 motor and then the piston hieght works out nearly perfect on a short block. 2.0l crank at 83.5mm would be around 2040cc displacement.

The ideal motor is the early Audi A4 1.8 20V motors.

Contact Viper (AKA Wikus) at GW Delarey, he built a meth fed 1.9. Ask him what he used piston and block wise, or read his build thread for his Citi race car.

I'm currently running a 1.9l short block U-flow motor and helped a friend in Scottburgh build a similar motor. We are both very happy.
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Re: 1900 build

Post by panic-mechanic »

Squish pad must not stick out more than 0.8 mm.
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Re: 1900 build

Post by merlinvenn27 »

panic-mechanic wrote:Squish pad must not stick out more than 0.8 mm.
I assume the top of the piston??
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Re: 1900 build

Post by Killerwatt »

0.8mm above block.
Also consider machining/balancing the intermediate shaft.
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Re: 1900 build

Post by panic-mechanic »

yes highest part of the piston.
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Re: 1900 build

Post by merlinvenn27 »

Killerwatt wrote:0.8mm above block.
Also consider machining/balancing the intermediate shaft.
Why? Isn't that done when using the 2lt crank to make a 2lt shortblock?
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Re: 1900 build

Post by missioner »

panic-mechanic wrote:Squish pad must not stick out more than 0.8 mm.
At 0.7mm they touch the cylinder head.

I recommend 0.4 if you plan on using octane booster or E50 or E85

Flush with the block will let you run on pump gas.
Last edited by missioner on Thu Apr 12, 2018 6:52 pm, edited 1 time in total.
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Re: 1900 build

Post by missioner »

merlinvenn27 wrote:
Killerwatt wrote:0.8mm above block.
Also consider machining/balancing the intermediate shaft.
Why? Isn't that done when using the 2lt crank to make a 2lt shortblock?
That's because the no.4 Conrod touches the intermediate shaft at the distributor gear end, it also touches the block above the oil pump and on a protrusion with the no.3 Conrod.

This is only a problem if you are building a short block 2.0l. That means taking a 1.6/8 motor and converting it using a 2.0l crank and pistons.

In your case you have a 2.0l motor already and want to build a 1.9l. This can be done, but the essential item is still the 1.8l crank. Without it the desired capacity cannot be reached. Once you have a crank then using a long block (2.0l) is actually better than a short block due to the reduction in Conrod angle at 90° before and after TDC. This reduces the stress on the Conrod and makes them less likely to break if you put your motor under duress at very high revs.

As I said in a previous post the best crank for your build is from an early 1.8 20v Audi motor.

Happy hunting.
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Re: 1900 build

Post by panic-mechanic »

Missioner- WHOA boy. Stop the bus.
His original post says he has an AFX motor that he wants to make a 1900. That means it is a 1.6i motor from a citigolf. He is not starting with a 2l and making it into a 1.9. So no need for intermediate shaft anything mods etc.
Oh and I have built probably in excess of a 100 of these things and have always used 0.8 mm as the squish pad piston protrusion. we rev them to 7800 and not ever had a piston touch. You have to use the steel gasket.
Also never had one break a rod and they rev quite happily.
Oh yes running them on 95. 11:1 CR
So a fair amount of what you are saying here is simply confusing / alarmist info.
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Re: 1900 build

Post by Killerwatt »

Have to agree with panic 0.8 is fine. Stock gasket is 1.2 to 1.3mm compressed so you should not be touching the head. Unless you removed a layer from the gasket or have excessive bearing clearance.

Also I was not talking about machining the gear on the intermediate shaft for clearance. The stock intermediate shaft is a casting and only the bearing journals and gear spigot are machined.
Often the cast part of the shaft is not concentric to these machined surfaces. If you spin a shaft on a lathe you will see what I mean. Some are much worse than others, I had one on the lathe that needed about 8mm removed on the cast surface before the shaft was concentric.

Also increasing the rod ratio does not really help with conrod strength. You would have a tiny bit less sideloading on the piston though. Honestly stock 8v conrods will be fine at high revs, but you can upgrade the bolts if you really want to.
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Re: 1900 build

Post by panic-mechanic »

Yeah intermediate shafts are far from being cast perfectly that's for sure.. Makes for a smoother motor when you machine them nicely.
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Re: 1900 build

Post by missioner »

panic-mechanic wrote:Missioner- WHOA boy. Stop the bus.
His original post says he has an AFX motor that he wants to make a 1900. That means it is a 1.6i motor from a citigolf. He is not starting with a 2l and making it into a 1.9. So no need for intermediate shaft anything mods etc.
Oh and I have built probably in excess of a 100 of these things and have always used 0.8 mm as the squish pad piston protrusion. we rev them to 7800 and not ever had a piston touch. You have to use the steel gasket.
Also never had one break a rod and they rev quite happily.
Oh yes running them on 95. 11:1 CR
So a fair amount of what you are saying here is simply confusing / alarmist info.
Sorry my bad.

I used the fibre gasket with my build and had the squish pad touch the head very slightly at 0.7mm protrusion.

Also I live lots closer to the coast than JHB, I still have pinging when I go closer to Durban and my pistons are flush with the block now. No money for OB.
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Re: 1900 build

Post by missioner »

Anyhow thanks for clearing that up both of you guys.

I'm sorry for any confusion I have caused.
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merlinvenn27
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Re: 1900 build

Post by merlinvenn27 »

panic-mechanic wrote: Fri Apr 13, 2018 7:38 am You have to use the steel gasket.
Also never had one break a rod and they rev quite happily.
Oh yes running them on 95. 11:1 CR
Cometic head gasket???
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Re: 1900 build

Post by panic-mechanic »

Well essentially yes but you just walk into a goldwagen and buy a steel one for a polo. cometic is a brand name.
These are made by Elring or Victor Reinz.
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