Speedster Engine Builds and Dyno Graphs

This is a 1904cc engine perfectly suited for a speedster. The cam is mild, with a low rpm flat torque curve. The carbs are 44mm Weber with 32mm venturi's, 1-1/2 A-1 sidewinder exhaust with heater boxes and a programmable magnaspark digital distributor. The engine is going to New Mexico, elevation is close to 4500 feet. This is why I did the programmable ignition, I wanted more ignition timing for the high elevation. When I have time, I will post a screen shot of the ignition timing table. I also raised the compression to 9-1 to help make up for the elevation hit the engine will see at 4500 feet.

This is a 2005cc engine also nicely suited for a speedster. This one was more of a hot rod build but still a nice daily driver. I used some nice flowing heads with 42x37.5 valves, dual weber 44 IDF carbs with 34mm venturi's, 256 deg duarion cam @.050 lift and an 1-1/2 A-1 Sidewinder exhaust. This engine will be a kick in the pants to drive.

Thank you Mr. Downs,

We look forward to the future of this thread...

Hi Pat Downs - do u plan to dyno a 2110 cc?  That's mine with 2 Dilordos, a mild cam, and Phat Boy exhaust.  I assume it won't be much more HP than the 2005cc above. - Thx - Dave

Much appreciation for you taking time from your busy day to share, Pat!

~WB

Pat you forgot to capitalize the B in Builds on the thread title. Damnit I hate having OCD. Is there any way you can fix that? Theron - can you fix it?

bUILD

Thanks Pat.  Knowledge is power.  So are extra cc's.  Don't know if this is time or place for this conversation but here goes.  Bought a 1999 Vintage Spyder with one of your 2109cc engines.  Had problems with oil leaks and loosening of intake manifold screws.  I would say that I did run the heck out of that car.  Track use etc.  I have some old never used Dells that I would like to use for a spyder build in a few years.  I am considering suby(no Dells), type 4 and type 1.  Would like to have 165-180 hp.  I'm sure that type 1 engine technology has improved to some extent since 1999.  If I was going with a type 1 in a spyder at this time what would you recommend considering that I will probably run the engine pretty hard?  Even though I had some problems with the 2109 I still consider you the best type 1 builder out there.  Don't know if you are willing to dive into the type 1 vs type 4 discussion but I would sure like to hear your thoughts.  Have engine cases and new type 1 technology improved enough to compare with type 4s as long as someone is willing to keep engine displacement in a reasonable range say less than 2.3 liters?  Sorry if this is too much.  Would be happy to call you.  Was planning to when the time was right.

The type-4 engine is strong by design. My issue with the type-4 is cost compared to the type-1. Parts quality has improved over the years and it has also declined on certain things. The job of an engine builder is to know what's good and what to stay away from.

    If you plan on racing a type-1 engine, heat is your biggest enemy. Heat destroys these engines and everything possible needs to be done to combat the heat that 170-180 horsepower creates.

    I am building a 2332cc engine for my dear friend Anand Rajani. We are using Nicasil cylinders along with a head casting that has very good cooling properties. Anand is going with the 4 cam shroud but I do not believe this is needed, he wants the shroud for it's looks. Compression and camshaft choice is critical also. Moderate compression, 9-1 to 9.5-1 with a low duration cam builds allot of cylinder pressure and detonation will be an issue.

   If you are leaning towards a type-1 engine, you should consider a modern programmable ignition. I am using a programmable crank trigger ignition with coil on plug on Anand's 2332cc. This allows me to design a spark table around Anand's driving style, eliminating detonation while still allowing him to have a cam in the 250 degree @.050 lift range.

  So, My answer to you is yes, a type-1 engine can be built to hold up to 170 HP, driven on the street and raced occasionally. It just needs to be designed differently than your average engine.   

Your best choice for the engine size IMO is a 2276cc. I would use a VW rod crank due to the fact it has more cross sectional area between the main and rod journals than a 2" chevy/buick journal. I would also recommend a head casting like what I am using on Anand's engine, the O.E 043 casting from VW.

    I know they are expensive but Nicasil cylinders are your biggest adversary on reducing heat. I highly recommend them if you want a dual purpose race/street car.

   If you would like to call me, I would be happy to talk to you in more detail. I can PM you my personal cell#.

Pat.  Thank you so much for your response.  I currently drive a watercooled 356 and will likely keep it as my long distance ride.  But I want a spyder that I can keep at a mountain home.  Think I'm going to stay off the track but I do want it for spirited mountain drives.  No pampering.  Its nice to know that there is still reliable power from a type 1.  I want the spyder to be light and nimble.  I also owned a suby spyder after the aircooled spyder.  I always liked the handling of the aircooled car better even though it was not as fast.  I should have kept that first spyder.  Live and learn.  I will contact you after my financial commitments to my final child are complete in a couple of years.  Thanks again.

I have heard this said many times, "Disconnect the temp gage and just drive the car". I don't agree with that statement. Pat I sure would like to get your opinion on what a reasonable operating temperature is on a 95 degree day and is it obtainable in a 2110.

Can you give us some tips on cooling for the bigger motors? 

Pat- In the 1904 in your 2nd post, do you remember which cam the engine had? And I'm assuming (please correct me if I'm wrong) you used 40x35 heads? Were they ported or as cast? And if this is so, how do you think that engine would react using some properly ported 35x32 heads instead? Thanks for spending the time here. Al

Al:  Specs for their popular turn-key engines are up on CB's website.  

Look here:  http://www.cbperformance.com/S...hResults.asp?Cat=138

Alb, I used the #2280 cam with 1.25 ratio rockers and some CNC ported round port heads with 40x35.5 valves on the 1904cc engine. I would expect to loose about 12-15 horsepower with an unported 35.5mm x 32mm valve head.

If you were to port the 35.5x32 valve heads, the power loss would be 5-7 IMO. It all depends on how the heads flow compared to the cnc ported 40x35.5 valve heads.

Pat, what about the bottom end/lower midrange part of the torque curve? I'm of the understanding that a pair of properly ported 35x32 heads will produce 120-125 hp, and with a < 2 liter engine that only produces 123hp wouldn't it be better to use a good set of stock valve heads to keep intake tract air speed higher in the lower rpms for better driveability and mileage, or am I missing something here? Afterall, this is an engine that doesn't begin to take advantage of the capability of a pair of even lightly ported 40x35 heads.

And feel free to call me Al (come on; you know the tune).

Any engine size is going to respond to increased airflow. It is a give and take, increased air flow will gain mid and higher rpm horsepower, low end will fall off slightly. Again, it all depends on the heads, intake port velocity, exhaust port, combustion chamber.

      Smaller valve heads do have more port velocity due to the small port but it takes some rpm to make 120-130 HP from a small engine, they don't make it down low because they suffer on torque due to their size. It's going to take some air flow to make this kind of power, you are going to need a good flowing head using a 35.5mm intake valve to do it.

Here is another build for a 356 speedster. This customer wanted a smooth running engine with very good fuel economy. He wasn't concerned about a ton of HP, he just wants to take long drives with his wife with low maintenance.

   I built him a 74mm stroke x 90.5mm bore engine, 1904cc. I used some un-ported 043 casting heads with 35.5mm intake and 32mm exhaust valves with heavy duty single valve spring and chromoly retainers. Carburetion is a pair of Single throat 34mm ICT Weber carbs and a mild cam on a 112 degree lobe center. By spreading the lobe separation to 112 degrees, I decreased the amount of overlap on the intake/exhaust lobes. This helps to keep un-burnt fuel going out the tail pipe, improving fuel economy. 

   The engine runs extremely smooth and still pulled slightly over 100 HP. It made great torque, 137 ft lbs.  

That is a really great build, by the numbers. 130 ft-lbs right through from low 2000s to almost 4000 rpm, 100 HP flat from like 4200-4800 or so. On the road, in a Speedster, that should feel plenty strong and require no thought with the shifter.