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Sun Feb 15, 2015 8:20 am

I have a 1600lb kit car built on a VW chasis. This is not my daily driver nor ever will be, it is a fair weather car with only a partial top and no side windows. I only drive it in the summer and when there is no chance of rain. I live about 3 miles outside of town so i drive it at 60mph 3K RPM on an old paved road when i head to town. It runs hot at 60 and would not hold up long at higher RPM. (cooling the engine down is next on my list) Thats as fast as i take it, though it would be nice to be able to run it 70mph and be able to drive on the highways.

My engine is a newly installed 1835cc piston and cylinder kit on a dual port engine. Have a free flow exhaust installed. I just installed a set of used dual single port Kads. Everything else is bone stock. It runs pretty well but doesnt have the power of a true sports car.

I would like to be around 100hp or maybe a tad more. Since i only drive it enough to go through maybe 2 tanks of gas a year i was thinking about simply upping the compression ratio to get me up the hp numbers id like. I can buy royal purple race fuel locally and run solely on that. That would be a dirt cheap way of getting more performance from it. Yes i know the cost of race fuel, but like i said it doesnt get driven a lot so the cost of gas isnt a concern to me.

My main questions are whats going to happen to my engine if i bump the compression up to 10.5:1 or so? Is it going to run much hotter than it is now? What negative effects are going to pop up that i havent thought of?

Sun Feb 15, 2015 8:33 am

I don't know anything about engines... So... How are you planning on increasing comp? Sounds like you want something bolt-on without having to split the case or do major work.

Sun Feb 15, 2015 8:39 am

did you put in a cam and heads?

you wont get 100hp out of a stock cam/ heads no matter how high you put the comp ratio......if it was that easy, everyone would be doing it.....

Sun Feb 15, 2015 8:42 am

Fast, Cheap, Reliable, pick 2, you can't have all 3. Before you do an ything find out why your car is running hot BEFORE you up your HP. What body is the kit car designed after. Some have inherent cooking problems. Hp is made in the cylinder heads, the more efficiently you get air in and out the more HP you make. Stock heads and Kadrons, it will be tough to make hp. You have enough displacement to make 100hp fairly easy, you'll just have to spend money on parts.

brad

Sun Feb 15, 2015 9:03 am

Easiest way- pull it apart and put a cam in it with some ported stock valve dual ports.

So with your non existent budget, forget it.

And no, race fuel will not give you more power unless your engine was built for it.

Sun Feb 15, 2015 9:05 am

Before you do anything to the engine you need to solve your cooling issues. Post several pictures maybe we can help.

Getting dual IDF's would do more good then raising the compression and running race gas.

Sun Feb 15, 2015 9:21 am

Wait, is it a dual port or single port??

Sun Feb 15, 2015 10:00 am

The question is how did he get the single port Kad's on the dual ports, wild stuff.

Sun Feb 15, 2015 10:10 am

GTV wrote: Wait, is it a dual port or single port??

Different heads. Single port is the older, and more reliable, design. One single intake port feeds both intakes on the head. Dual port as two separate, but very close together intake ports on the head. As originally from VW it had a larger bore in take manifold that split the air into the two separate ports a few inches before the heads. You can also get intake manifolds that keep each intake separate.

Spend a few evenings reading the posts on the performance forum. You will be amazed at what these guy can to and amazed with their knowledge. I guarantee you will learn lots.

Sun Feb 15, 2015 10:28 am

Thanks, but I've spent over half of my life deeply involved in the ACVW community. I'm astutely aware of the differences between single and dual port heads.

gitrdun wrote:
I just installed a set of used dual single port Kads.

It could be that he has single port heads, or he has dual port heads but isn't familiar with VW lingo and is referring to Kadron's as single port (butterfly) carbs. vwracerdave suggested that he upgrade to IDF's, which as you may or may not know, would be challenging to adapt to single port heads. Hence my query.

Sun Feb 15, 2015 10:42 am

By single port carbs i mean they are a single barrel carb one on each head, the heads are dual port. The car body is an old Bradley GT. There is no way to seperate the upper and lower sides of the engine like in a bug to keep the hot air and cool air seperate. My heads are stock dual ports. Far as i can tell they have been machined to accept the larger cylinders.

My plan is to pull the engine and remove the heads to measure and check my deck clearances, i suspect something is amiss in that area. Also is missing the lower tins so that will need to be addressed when the engine is out. I do not have the heater boxes installed or any of the tin and venting that goes with that.

I am not against putting in a good cam or changing the rocker ratio's. There are so many options out there for these motors i just dont know what i need to get the hp i want from the engine.

Heres what i would like to get. 100hp-120hp around 3500RPM. Really dont expect to be running this thing at 100MPH down the highway, 0-60 is what im after. I have kids and id like to be around long enough to have grandkids someday. Running on 91 octane pump gas or can run race fuel if the compression has to come up.

So point me at the parts i need to make it happen please. And i assume my single port kad's are better than the stock restrictive carb and intake, is that correct?

Sun Feb 15, 2015 11:22 am

Before we can make suggestions we need to know what you currently have. Details about cam, heads, compression and exhaust. Just raising CR and running race gas is not going to get the results you are after. I'm guessing you will need a new cam, bigger heads and larger dual IDF carbs.

What transaxle gearing and tire size do you have? That will also have a big effect on 0-60 times.

Sun Feb 15, 2015 11:54 am

Ok. Stock transmission and clutch, 78-14 rear tires, engine is all stock dual port 1600 except for the following mods. 1835cc pistons and cylinders, dual single barrel Kadrons, EMPI baja exhaust. Dont remember exactly what compression is right now, im thinking around 7.5:1 . Car weighs apx 1600lbs.

I dont need a 0-60 dragster i just want the power down at a usable speed level, not something thats gonna roar at 90mph and 6K RPM.

Sun Feb 15, 2015 11:57 am

Well there you have it.

Using a better than stock cam, something in the Engle 110 neighborhood will give you a good amount of power with solid torque. The heads will need to be upgraded, the power is in the heads so spend your money there. I'd go with some decent 40x35.5's, ported. Give it about 9:1 compression with .040" deck. Dual 40 Webers.

Plan on spending $1000-1500 depending on how thrifty you are.

Or sell the Kadron's and slap a turbo on it.

Sun Feb 15, 2015 12:05 pm

You have touched upon your basic problem: no way to separate the upper/cool air entry and the lower/hot air expulsion. That, and not having all the engine tin in place and fit well.
Both of those will have to be FULLY addressed before you can resolve the heating issue.
Since that will be a labor-intensive task that almost no one but a fanatic (and Gene Berg) would complete I suggest the easy way out.
Have a 1.42 third and a 1.04 fourth installed in your transaxle and just resign yourself to rebuilding your engine every year or so.

Sun Feb 15, 2015 12:06 pm

gitrdun wrote: Heres what i would like to get. 100hp-120hp around 3500RPM. Really dont expect to be running this thing at 100MPH down the highway, 0-60 is what im after. I have kids and id like to be around long enough to have grandkids someday. Running on 91 octane pump gas or can run race fuel if the compression has to come up.

100-120hp at 3500 rpm means 150-180 ft-lbs of torque at 3500 rpm. With good heads, carbs, and exhaust, you might be able to get the lower end of that with a normally aspirated 2276 or 2332cc engine, but I'd consider it to be impossible with your current engine. The only way you'd get close with your current engine is going turbo, and even that may require additional changes to the current engine config to support it properly.

But adding that much additional heat isn't going to do you any favors with your existing cooling problems.

Sun Feb 15, 2015 1:33 pm

Gotta be lucky and find a better set of used heads with matching manifolds and IDF carbs and linkage and then cam with high lift rockers to go with it will get you there....nothing free.

Sun Feb 15, 2015 2:36 pm

You can always fab tin to bolt to the motor to extend the factory pieces. Even if you can just extend the sides and rear of the tin it will help a lot. To get your HP I would add a 110 or equivalent cam, 1.25 rockers, 40x35.5 heads and 9 - 9.5:1 compression The Revmaster 049 heads look pretty good right out of the box and look to be about the best flowing non ported heads out there.

brad

Sun Feb 15, 2015 3:22 pm

I think an 1835 with a free flow exhaust and dual 40's ought to be plenty of power for a Bradley GT, even with stock heads. If it's overheating now, bumping the compression will only make it worse. I suspect you either have a timing issue or a vacuum leak. Or both.
I think I'd be finding a way to separate the upper engine compartment from the lower to keep the hot air out, I'd make sure those intakes have no vacuum leaks and I'd give the timing a thorough checkout. the distributor might not be advancing properly if it's a cheapie.
Your current set-up should have that BGT going well over 60 or even 80 MPH with ease.
It might take a little creative sheet metal work to isolate the top of the engine compartment, but that's cheap work. The rest of the tuning is free, unless you're paying a mechanic.

PS. The buggy flying in my avatar was running an 1835 with stock heads and dual Kadron 40's when that picture was taken.

Sun Feb 15, 2015 3:27 pm

Do you have a stock crank or an counterweighted crankshaft?

Read this article completely 2-3 times. http://www.aircooled.net/vw-performance-engines/ Basically you need a bigger cam, larger improved heads, and bigger dual IDF carbs. exactly how much bigger depends on the thickness of your wallet.

Read the stickie "Transmissions For Dummies" in the HBB Off-Road Forums to learn exactly which stock transaxle you have.