E85 and boost, what compression ratio could I run? - Page 3 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 09-06-2017, 04:16 PM   #41
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,967
Total Cats: 1,447
Default

run 15:1 and 30psi. For science
aidandj is offline   Reply With Quote
Old 09-06-2017, 04:22 PM   #42
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,044
Total Cats: 2,557
Default

I genuinely wonder how high you can go on a dinky BP head before you run into serious issues
18psi is offline   Reply With Quote
Old 09-06-2017, 04:26 PM   #43
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,967
Total Cats: 1,447
Default

Try these and let us know


Last edited by aidandj; 09-06-2017 at 04:44 PM.
aidandj is offline   Reply With Quote
Old 09-06-2017, 05:04 PM   #44
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,723
Total Cats: 243
Default

Quote:
Originally Posted by 18psi View Post
I genuinely wonder how high you can go on a dinky BP head before you run into serious issues
What serious issues would you run into? Lift the head? crack the head?

LOL on the rods!
patsmx5 is offline   Reply With Quote
Old 09-06-2017, 05:35 PM   #45
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,044
Total Cats: 2,557
Default

e85 does knock/detonate with enough craziness thrown at it, so there's that.
and then there are the physical load limits you mentioned
18psi is offline   Reply With Quote
Old 09-06-2017, 08:51 PM   #46
Senior Member
iTrader: (6)
 
Join Date: Jun 2010
Location: San Rafael, CA
Posts: 1,109
Total Cats: 37
Default

Quote:
Originally Posted by patsmx5 View Post
Using your calculator, my current setup with 84mm bore, 85mm stroke, 5.233" rods, 9:1 compression, 50* ABDC inlet valve timing, and 40 PSI boost, I get
7.96 dynamic compression ratio
29.62 effective boost compression ratio.

That is already significantly over your 18:1 sane numbers.


If I ran 12:1 and 35 PSI boost:
10.57:1 dynamic compression ratio
35.74:1 effective boost compression ratio.
That's beyond where I would be comfortable. Kudos for boosting "All of it".

At 20 psi you're at 18.77 dynamic with the same above info. Again just my target on race gas or E85 in a highly stressed environment. YMMV. In for results.
k24madness is offline   Reply With Quote
Old 09-06-2017, 10:44 PM   #47
Elite Member
Thread Starter
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,723
Total Cats: 243
Default

Quote:
Originally Posted by 18psi View Post
e85 does knock/detonate with enough craziness thrown at it, so there's that.
and then there are the physical load limits you mentioned
Yeah, I think I have octane to spare right now. At least for how I use the car, which is street and drag.


Quote:
Originally Posted by k24madness View Post
That's beyond where I would be comfortable. Kudos for boosting "All of it".

At 20 psi you're at 18.77 dynamic with the same above info. Again just my target on race gas or E85 in a highly stressed environment. YMMV. In for results.
My spring pressure for wastegate is 30 psi.

So if you consider 18:1 safe for track, and I have gotten away with 29.62:1 effective compression ratio, that is quite a difference. Do you think you could run more boost, or more compression on your setup?
patsmx5 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
E85 Naturally Aspirated Tuning Thread albumleaf Engine Performance 20 01-23-2017 08:06 PM
High Idle Issue in NA6 Philly Miata General Miata Chat 13 08-30-2016 12:51 PM
Loud grinding/rumbling/vibration on full boost / high rpm Jack P General Miata Chat 4 08-03-2016 07:27 PM
fuel pump wont run talisker MEGAsquirt 5 08-03-2016 03:16 AM
Won't rev past 4k, stalls, dies, rough idle. Can I get some help? 10100111001 General Miata Chat 0 08-02-2016 09:08 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 03:11 PM.