Hey guys,

I am having a 2270 built, 78mmx96mm. We are using the 163/86b webcam and 2.0l heads. Dellorto 45s and msds headers.

I am trying to decide on the right compression. The build is aimed at aggresive street use. I want to have as much power as possible and not have to run an external oil cooler or have any problems with detonation on 93/4 octane gas.

I have heard anything from 8.5:1 to 9.5:1. Please let me know your thoughts.

Thanks,

Andrew

First, sarcasm.
I want a brand new Ferrari, does not mean I will get one.
Unless you only want to drive from October to March, you will need better oil cooling.
This is an oil cooled motor.

8.5:1

9:1

Yeh
Not using a external oil cooler for aggressive street use

This doesn't sound like a recipe for long life or high output

On advice from my parts supplier I have gone 9.1:1 but with the essential external oil cooler and Porsche fan. Pic to post very soon I hope.....

Carbs or fuel injection?

Mine runs 10,3:1 with FI and has no knocking issues but I run premium 98 RON octane.

I'll throw my votes in...

8.5:1 - Very safe on regular gas.
8.7:1 - Still safe, but starting to push things. Regular gas is probably still okay.
9.0:1 - More power, but you gotta pay attention for heat and detonation are starting to become serious factors. Premium fuel would be best.
9.3:1 - This level can't use the word safe at all. You must shed the heat and you must be very conscious of detonation/pinging.
9.5:1 - You better know what you're doing, at all times. This is no longer a jump in a drive motor, this is a motor that you must constantly be listening to and feeling. Above premium fuel is necessary.

Mark, for future reference and general knowledge... Could you please clarify what you mean by regular vs. premium gas?

87ish octane low grade pump gas for regular 91ish premium pump gas for premium? Above premium = 95+ race fuel you get at the track?

I've only ever put the Shell V-Power in my car. I'm certain it's overkill for a stock 1.8.

You got it. I'm speaking under the assumption that Regular = 87, Midgrade = 89, and Premium = 91. These are the most commonly available octane ratings. While 93+ is available a lot of places, it's worth considering that if you take a road trip, the higher octane fuels may not be available. An engine that runs on race gas can be a ton of fun, but you're restricted to staying within range of your fuel source.

Like everything, it's about knowing what you want from your car/engine. The answer is different for everyone, it's good to talk to other people and see what they're doing, but at the end of the day your car should fit YOU.

Mine is at around the high side of 8.7. Still working out the fine tuning on the FI and had a few setup issues during the dyno testing. But without pushing super hard it this got me a max of right at 114 HP and 125 ft/lb of torque. Running premium 100% gas.

Even with external oil cooler still had some heat issues. Been adjusting the timing table in the cruise zones and seeing it drop quite a bit.

At this point, with those numbers it is fun to drive and has not demonstrated any really bad tendencies toward detonation or pinging.

8.25:1 on my 2.2 FAT Performance built type IV. 147 hp on the dyno. More than than that would probably require more trips to traffic school.

I will run Weber 44 IDF's - first test run out of the car in the next few weeks with a bit of luck....

Thanks very much for all responses. This build has been a great learning process.

Keep em coming.

Determine your dynamic compression:

http://www.wallaceracing.com/dynamic-cr.php

Try and keep it around 8:1

Static CR doesn't really matter.

-Aaron

Sounds like a fun project.
Power make heat as it’s waste product.
Basic physics.

Please monitor head temps as well as oil temps.

Aaron, tell that to your starter!

Thanks for all the input guys> I will post pics of the finished product.

Is there a specific reason you're running DRLA45's? I ran DRLA40's on my 2270 and it was perfect. Head temps around 325F and AFR avg around 12.8-13.2.
I also had Tangerine headers and an external oil cooler, btw.
But I think 45's might be a bit big. Anyone else have thoughts on that?

I recommend mid-grade (89 octane) gasoline for all stock 914-4 engines.
87 octane may ping under load going up hills. Premium is a waste of money, and it contains less energy than mid.

The only reason I use Premium is that at times gas stations cross dump thier fuels. Most often the low grade into the mid. So it is more likely you get a lot of 87 being sold as mid.

I decided on the 45s based on some research done here on the forum.

I consulted the engine builder as well who thought they would work fine, or that they could be configured to work very well. He did not think they would be too big for the displacement.

most 2270 kits suggest EMPI 44s no?

You want 45's. There is a formula for single cylinder displacement vs. RPM. Unless you are going to run it at 4000 RPM, you will be well within the range of 45's.

I ran 45s with my 2270. It was good! Have them on my 2316 now? Still good? YEAH!
Deck heights very important. Don’t run greater than 0.040 / 1mm. (that’s 40 thousandths ) then just calculate the static CR. Have the heads fly-cut then if you want a higher CR. I ran a 9.5:1.

9.5 on my 2056. Oil temps seem reasonable. CHT/EGT are right where I want them. I'm going to re-install my external oil cooler as some additional cooling, just because.

Bump it up that cam needs at least 8.8 to 9.0CR the one caveat is your jetting and timing needs to be bang on. You definitely need a wide band O2 meter and a head temp sensor under the #3 plug.
I'd start with an AFR of 12.5, keep it on the rich side with timing no more than 28* total. Running rich the fuel charge actually cools the heads a fair bit.

I have the same cam on my 2.6 with 9.3CR, but I have nickies and running a hybrid DTM (copy)/joe cali cooling system in a 400lbs lighter '67 bug. No over heating issues, no extra cooler. I can run extra CR because of the nickies.

As long as your head temps are no more than 325* cruise, 350* (maybe a hair more) pulling a hill and recovers every time on the downhill side you're OK.
Never lug the engine with this combo, 3k rpm minimum, even in trafic or downhill.

Andrew -
curious what you ended up going with for compression ratio and if you ever finished up your 2270? I am currently building one as well for a 912E. With a .040" deck height provided by a .040" cylinder shim I would be right at 9:1. I am building a Raby 2270 based upon the 2270-175 kit from the type 4 store.

Brook

Yeah except that EMPI 44 carbs are based on Webers. Dellorto sizes aren't the same. DRLA40's flow like Weber 44 IDF's. DRLA45's will be like having Weber 48's.
My engine was built by McMark, who used the DRLA40's on my 2270.

This deserves clarification. Out of the box dellorrtos came with larger sized vent than the equivalent weber. Of course they flowed more. for example a idf 40s had 28mm vents, Drla 40s came with 32s.

Dellorttos advantage is the number of progression ports and easier tuning with access to the jets on the top of the carb. Drawback is that they are NLA.

I'm at 9.3:1 163/86b doesn't wake up till 3k.
My 500th post only took 16 years.

My DRLA 40's came with 28 vents and I sourced some 34's.

DRLA's are no longer available new but they aren't that hard to find used.

I don’t know anything about them, but EMPI has released a Dellorto like carb.

http://vwcatalog.empius.com/vwcatalog/2018/82.html

The “D” Series.