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> 2270 build, 2270 compression question
Alapone
post Jul 16 2018, 07:26 PM
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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
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r_towle
post Jul 16 2018, 08:38 PM
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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.
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r_towle
post Jul 16 2018, 08:38 PM
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8.5:1
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ConeDodger
post Jul 16 2018, 10:15 PM
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9:1
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thelogo
post Jul 17 2018, 12:00 AM
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Yeh
Not using a external oil cooler for aggressive street use

This doesn't sound like a recipe for long life or high output (IMG:style_emoticons/default/smoke.gif) (IMG:style_emoticons/default/chair.gif)
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wysri9
post Jul 17 2018, 12:46 AM
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QUOTE(thelogo @ Jul 16 2018, 11:00 PM) *

Yeh
Not using a external oil cooler for aggressive street use

This doesn't sound like a recipe for long life or high output (IMG:style_emoticons/default/smoke.gif) (IMG:style_emoticons/default/chair.gif)


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.....
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falcor75
post Jul 17 2018, 05:28 AM
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Carbs or fuel injection?

Mine runs 10,3:1 with FI and has no knocking issues but I run premium 98 RON octane.
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McMark
post Jul 17 2018, 05:30 AM
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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.
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troth
post Jul 17 2018, 06:18 AM
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QUOTE(McMark @ Jul 17 2018, 07:30 AM) *

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.
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McMark
post Jul 17 2018, 08:49 AM
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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.
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Mblizzard
post Jul 17 2018, 08:51 AM
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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.
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Elliot Cannon
post Jul 17 2018, 10:22 AM
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8.25:1 on my 2.2 FAT Performance built type IV. 147 hp on the dyno. (IMG:style_emoticons/default/driving.gif) More than than that would probably require more trips to traffic school. (IMG:style_emoticons/default/sad.gif)
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wysri9
post Jul 17 2018, 10:36 AM
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QUOTE(falcor75 @ Jul 17 2018, 04:28 AM) *

Carbs or fuel injection?

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


I will run Weber 44 IDF's - first test run out of the car in the next few weeks with a bit of luck....
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Alapone
post Jul 17 2018, 10:50 AM
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Thanks very much for all responses. This build has been a great learning process.

Keep em coming.
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yeahmag
post Jul 17 2018, 12:19 PM
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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
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r_towle
post Jul 17 2018, 06:08 PM
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Sounds like a fun project.
Power make heat as it’s waste product.
Basic physics.

Please monitor head temps as well as oil temps.
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ConeDodger
post Jul 17 2018, 06:40 PM
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QUOTE(yeahmag @ Jul 17 2018, 03:19 PM) *

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


Aaron, tell that to your starter! (IMG:style_emoticons/default/av-943.gif)
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Alapone
post Jul 18 2018, 06:35 AM
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Thanks for all the input guys> I will post pics of the finished product.
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era vulgaris
post Jul 18 2018, 08:27 AM
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QUOTE(Alapone @ Jul 16 2018, 09:26 PM) *

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


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?
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ChrisFoley
post Jul 18 2018, 08:51 AM
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QUOTE(troth @ Jul 17 2018, 08:18 AM) *

QUOTE(McMark @ Jul 17 2018, 07:30 AM) *

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.

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.
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