Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG. This site is not affiliated with Porsche in any way.
Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners.
 

Welcome Guest ( Log In | Register )

> Engine swaps, Mpg focused
r_towle
post Jun 1 2022, 08:08 PM
Post #1


Custom Member
***************

Group: Members
Posts: 24,594
Joined: 9-January 03
From: Taxachusetts
Member No.: 124
Region Association: North East States
Leave the SBC and flat6 conversions out of this.

Who has swapped a different engine into a 914?
Something Japanese, great mpg?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
2 Pages V  1 2 >  
 Reply to this topicStart new topic
Replies(1 - 19)
mepstein
post Jun 1 2022, 08:17 PM
Post #2


914-6 GT in waiting
***************

Group: Members
Posts: 19,325
Joined: 19-September 09
From: Landenberg, PA/Wilmington, DE
Member No.: 10,825
Region Association: MidAtlantic Region
My stock 1.7 would easily get 38-40 mpg on the highway at 70-75mph. Why bother with an engine swap. Just use a 1.7 in good tune and the right tires.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Robarabian
post Jun 1 2022, 08:35 PM
Post #3


914 A Roo
***

Group: Members
Posts: 593
Joined: 11-February 19
From: Simi Valley, Kalifornia
Member No.: 22,865
Region Association: Southern California
When I am not hard on the Turbo, my Subaru 2.0 WRX motor does 30 MPG highway....

Its good around town, but my foot is always in it so hard to say how efficient it could be.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Montreal914
post Jun 1 2022, 08:57 PM
Post #4


Senior Member
***

Group: Members
Posts: 1,594
Joined: 8-August 10
From: Claremont, CA
Member No.: 12,023
Region Association: Southern California
QUOTE(mepstein @ Jun 1 2022, 07:17 PM) *

My stock 1.7 would easily get 38-40 mpg on the highway at 70-75mph. Why bother with an engine swap. Just use a 1.7 in good tune and the right tires.


WOW! those are great numbers! (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/driving.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mepstein
post Jun 1 2022, 09:09 PM
Post #5


914-6 GT in waiting
***************

Group: Members
Posts: 19,325
Joined: 19-September 09
From: Landenberg, PA/Wilmington, DE
Member No.: 10,825
Region Association: MidAtlantic Region
QUOTE(Montreal914 @ Jun 1 2022, 10:57 PM) *

QUOTE(mepstein @ Jun 1 2022, 07:17 PM) *

My stock 1.7 would easily get 38-40 mpg on the highway at 70-75mph. Why bother with an engine swap. Just use a 1.7 in good tune and the right tires.


WOW! those are great numbers! (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/driving.gif)


My 2.0 with a hot cam and carbs was more like 25-28
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
r_towle
post Jun 1 2022, 09:29 PM
Post #6


Custom Member
***************

Group: Members
Posts: 24,594
Joined: 9-January 03
From: Taxachusetts
Member No.: 124
Region Association: North East States
I got 48 mpg from my tuned 1.7 with djet….and I really learned djet that year.
And I learned all about low roll resistant tires….which are great for mpg but suck for traction
But I digress.
Just curious if anyone put a newer FI engine like a Toyota or Honda into a 914
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Dave_Darling
post Jun 1 2022, 10:20 PM
Post #7


914 Idiot
**********

Group: Members
Posts: 14,991
Joined: 9-January 03
From: Silicon Valley / Kailua-Kona
Member No.: 121
Region Association: Northern California
There's at least one VW turbodiesel out there. (Pre-TDI.) That would seem to be a great way to go for fuel economy, but I'd be concerned that the gearing would be too short to really do the diesel justice.

--DD
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
cali914
post Jun 1 2022, 11:23 PM
Post #8


cali914
**

Group: Members
Posts: 447
Joined: 26-April 06
From: Berkeley Ca.
Member No.: 5,934
Region Association: Northern California
I had a Honda J35 odyssey engine in my 914 210 hp getting 25 city and 30 highway. One of the smoothest engines i have ever swapped into a 914.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ogdougy
post Jun 2 2022, 12:01 AM
Post #9


Newbie
*

Group: Members
Posts: 49
Joined: 9-May 22
From: Arizona
Member No.: 26,536
Region Association: Southwest Region
Why not ee20?

Subaru flat 4 - it fits
Get it with the 6 speed trans - gearing good
Diesel - gets 40+ mpgs in the Forester. Heavy and AWD. Imagine the numbers it could make in a 914
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Arno914
post Jun 2 2022, 12:29 AM
Post #10


Member
**

Group: Members
Posts: 233
Joined: 13-May 20
From: near Frankfurt, Germany
Member No.: 24,260
Region Association: Germany
Just wondering. (IMG:style_emoticons/default/confused24.gif)
Does anybody really care about the fuel economy of his 914???
It is good, even to today´s standards and 914´s are so much fun to drive. So who cares about a mile less ore more on a tank?
(Just my 2 Cents...)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
sb914
post Jun 2 2022, 03:34 AM
Post #11


Surf Guru
****

Group: Members
Posts: 4,320
Joined: 25-November 12
From: Brookings,Oregon
Member No.: 15,191
Region Association: Southern California
QUOTE(Arno914 @ Jun 1 2022, 11:29 PM) *

Just wondering. (IMG:style_emoticons/default/confused24.gif)
Does anybody really care about the fuel economy of his 914???
It is good, even to today´s standards and 914´s are so much fun to drive. So who cares about a mile less ore more on a tank?
(Just my 2 Cents...)

(IMG:style_emoticons/default/agree.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mate914
post Jun 2 2022, 05:09 AM
Post #12


Matt
***

Group: Members
Posts: 760
Joined: 27-February 09
From: Eagles mere, PA
Member No.: 10,102
Region Association: North East States
QUOTE(sb914 @ Jun 2 2022, 05:34 AM) *

QUOTE(Arno914 @ Jun 1 2022, 11:29 PM) *

Just wondering. (IMG:style_emoticons/default/confused24.gif)
Does anybody really care about the fuel economy of his 914???
It is good, even to today´s standards and 914´s are so much fun to drive. So who cares about a mile less ore more on a tank?
(Just my 2 Cents...)

(IMG:style_emoticons/default/agree.gif)

(IMG:style_emoticons/default/agree.gif)
(IMG:style_emoticons/default/agree.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Front yard mechanic
post Jun 2 2022, 05:15 AM
Post #13


Senior Member
***

Group: Members
Posts: 1,174
Joined: 23-July 15
From: New Mexico
Member No.: 18,984
Region Association: None
QUOTE(mate914 @ Jun 2 2022, 03:09 AM) *

QUOTE(sb914 @ Jun 2 2022, 05:34 AM) *

QUOTE(Arno914 @ Jun 1 2022, 11:29 PM) *

Just wondering. (IMG:style_emoticons/default/confused24.gif)
Does anybody really care about the fuel economy of his 914???
It is good, even to today´s standards and 914´s are so much fun to drive. So who cares about a mile less ore more on a tank?
(Just my 2 Cents...)

(IMG:style_emoticons/default/agree.gif)

(IMG:style_emoticons/default/agree.gif)
(IMG:style_emoticons/default/agree.gif)

We need two hundred and fifty 2 cents to buy a gallon
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mayne
post Jun 2 2022, 06:36 AM
Post #14


Member
**

Group: Members
Posts: 254
Joined: 28-February 17
From: NM
Member No.: 20,880
Region Association: None
What about an early 1.6/1.8 Miata motor?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Superhawk996
post Jun 2 2022, 06:37 AM
Post #15


914 Guru
*****

Group: Members
Posts: 5,916
Joined: 25-August 18
From: Woods of N. Idaho
Member No.: 22,428
Region Association: Galt's Gulch
QUOTE(r_towle @ Jun 1 2022, 11:29 PM) *


And I learned all about low roll resistant tires….which are great for mpg but suck for traction
But I digress.
Just curious if anyone put a newer FI engine like a Toyota or Honda into a 914



You're on the wrong track with an engine swap. You were on the right track with low rolling resistance tires.

Fuel economy is a function of rolling resistance, aero dynamic drag, and parasitic drag.

Aero drag is almost a fixed variable based on body shape. 914 is already surprisingly good with flat underbody, small frontal area, and small side mirrors, you'll largely need a wind tunnel to tweak it any further. Someone did a nice CFD on 914 aero. If you are serious about trying to improve MPG, you can't ignore aerodynamics.

Here: http://www.cassidy-online.com/porsche914/a...aids/index.html

Tire are ABSOLUTELY the the largest rolling resistance variable you can easily affect. Look at Honda Insight (165/65R14) - skinny, low rolling resistance tires. Sounds a lot like stock 914 tires. But notice, the Insight went 14". That is to reduce inertia of the wheels vs. stock 914 on 15". The larger diameter wheel requires more energy (i.e. lower MPG) to accelerate the wheel up to speed after each stop. You'll also want to keep wheel mass as low as possible (carbon fiber would be ideal (IMG:style_emoticons/default/laugh.gif)). Big meats that look cool and provide awesome handling aren't going to get good MPG.

After that, you're chasing parasitic drag. Need to go to high roll back brake calipers (makes brakes feel crappy), low drag bearings and seals (differential, wheel bearings, etc.).

The actual engine has very little to do with MPG other than it needs to overcome rolling resistance, aero drag, and parasitic drag. As noted by Mark as well as your own claimed MPG, a stock 1.7L driven gently is going to be pretty respectable.

I'm curious if you got 48 mpg; what target MPG are you hoping for and for what purpose? How much gas could you buy with the money spent on the engine swap and/or pursuit of lowering parasitic loads?

If you want more fuel efficiency out of an engine, you're going to end up looking at something like 1.0 - 1.2L, 3 cylinder turbo charged engines.

The Mitsubishi Mirage 3 cylinder is 1.2L - about 76 HP. Sounds suspisciously like a stock 1.7L (IMG:style_emoticons/default/happy11.gif) but will have better Brake Specific Fuel Consumption than a 50 year old air cooled motor.

Or, there is the Ford Fiesta 1.0L 3 cylinder EcoBoost that is good for 123 HP. But if you're on the turbo and making 123 HP, you won't be getting best fuel economy (IMG:style_emoticons/default/av-943.gif) and we're back to square one. Same for the 3 cylinder out of the Mini Clubman which is 1.5L and 134 HP.
User is online!Profile CardPM
Go to the top of the page
+Quote Post
Superhawk996
post Jun 2 2022, 06:43 AM
Post #16


914 Guru
*****

Group: Members
Posts: 5,916
Joined: 25-August 18
From: Woods of N. Idaho
Member No.: 22,428
Region Association: Galt's Gulch
QUOTE(Mayne @ Jun 2 2022, 08:36 AM) *

What about an early 1.6/1.8 Miata motor?


Nope. 1st generation Miata is roughly the same weight as a 914 (2,000 lbs ish), similar frontal area, etc.

I had one from 1994 - 2018. About 30 MPG on highway, 24 MPG combined fuel economy per EPA.

https://www.fueleconomy.gov/feg/noframes/7490.shtml

A good portion of why the Miata MPG is so low is because of the tires. The messy underbody creating drag, and the poor aero drag due to the body design / convertible top shape don't help at all either.

If you're serious about MPG, you're going to end up having to do the engineering and it's not as simple as just swapping engines.

Note to tie into later post: 1st Gen Miata had a published Cd of 0.38 -- same as what I could find for the 914.
User is online!Profile CardPM
Go to the top of the page
+Quote Post
bbrock
post Jun 2 2022, 07:25 AM
Post #17


914 Guru
*****

Group: Members
Posts: 5,269
Joined: 17-February 17
From: Montana
Member No.: 20,845
Region Association: Rocky Mountains
QUOTE(Arno914 @ Jun 2 2022, 12:29 AM) *

Just wondering. (IMG:style_emoticons/default/confused24.gif)
Does anybody really care about the fuel economy of his 914???
It is good, even to today´s standards and 914´s are so much fun to drive. So who cares about a mile less ore more on a tank?
(Just my 2 Cents...)


YES! (IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/smile.gif)

Fuel economy has always been a big draw for me since I fell in love with these cars in the 70s. Performance and (IMG:style_emoticons/default/stromberg.gif) mileage? Not interested (IMG:style_emoticons/default/dry.gif) Performance and great economy? Sign me up. (IMG:style_emoticons/default/piratenanner.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mepstein
post Jun 2 2022, 07:35 AM
Post #18


914-6 GT in waiting
***************

Group: Members
Posts: 19,325
Joined: 19-September 09
From: Landenberg, PA/Wilmington, DE
Member No.: 10,825
Region Association: MidAtlantic Region
I think good mpg is a good measure of engine performance. Just like our cars, doing more with less.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Superhawk996
post Jun 2 2022, 07:36 AM
Post #19


914 Guru
*****

Group: Members
Posts: 5,916
Joined: 25-August 18
From: Woods of N. Idaho
Member No.: 22,428
Region Association: Galt's Gulch
QUOTE(bbrock @ Jun 2 2022, 09:25 AM) *

Performance and (IMG:style_emoticons/default/stromberg.gif) mileage? Not interested


(IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/slap.gif)


(IMG:style_emoticons/default/av-943.gif)

You can have both with a 914 -- respectable fuel economy but MOST importantly great handling. (IMG:style_emoticons/default/grouphug.gif)
User is online!Profile CardPM
Go to the top of the page
+Quote Post
Chris H.
post Jun 2 2022, 07:37 AM
Post #20


Senior Member
****

Group: Members
Posts: 4,032
Joined: 2-January 03
From: Chicago 'burbs
Member No.: 73
Region Association: Upper MidWest
QUOTE(r_towle @ Jun 1 2022, 09:08 PM) *

Leave the SBC and flat6 conversions out of this.

Who has swapped a different engine into a 914?
Something Japanese, great mpg?


This was Rich's the original question. If I had to do a different swap I would consider a K series with megasquirt. You could control the VTEC to keep the fuel economy up there but also kick it in early if you wanted some extra ooomph.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
« Next Oldest · 914World Garage · Next Newest »
 

2 Pages V  1 2 >
Reply to this topicStart new topic
2 User(s) are reading this topic (2 Guests and 0 Anonymous Users)
0 Members:

 

Display Mode: Switch to: Standard · Linear+ · Switch to: Outline

Track this topic · Email this topic · Print this topic · Subscribe to this forum

- Lo-Fi Version Time is now: 17th June 2024 - 01:46 AM
Invision Power Board v9.1.4 © 2024  IPS, Inc.
All rights reserved 914World.com © since 2002
914World.com is the fastest growing online 914 community!
We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ...