How to pick injectors for the LE5 - Pontiac Solstice Forum
 
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post #1 of 13 (permalink) Old 11-17-2010, 04:24 PM Thread Starter
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How to pick injectors for the LE5

Have been reading up on injectors and am trying to plan out what I'll need for the build. What are the ways to tell if you need high or low impedance, the required duty-cycle, size, etc? It seems like there's a crazy variance in types and options out there.....

Thanks in advance.
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post #2 of 13 (permalink) Old 11-17-2010, 04:30 PM
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looking forward to this- should be good

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post #3 of 13 (permalink) Old 11-17-2010, 07:02 PM
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Quote:
Originally Posted by idkfa View Post
Have been reading up on injectors and am trying to plan out what I'll need for the build. What are the ways to tell if you need high or low impedance, the required duty-cycle, size, etc? It seems like there's a crazy variance in types and options out there.....

Thanks in advance.
Why do you need larger injectors? What kind of build are you planning?

Dave

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post #4 of 13 (permalink) Old 11-17-2010, 08:23 PM
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Too many people just don't understand injectors. They treat them like bigger carbs on old style engines, when in fact they are really like richer jets, not bigger carbs.

Unless you have evidence that the current injectors can't supply enough fuel for your engine, LEAVE THEM ALONE!

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post #5 of 13 (permalink) Old 11-17-2010, 08:51 PM Thread Starter
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For now, it's just a simple bolt-on turbo upgrade with a garrett gt2871r. It'll be a mild tune for a daily driver until i start planing out more reliable power requirements (head studs, valves, etc). I know there have been some recommended injectors on this forum for similar sized turbos but I was really hoping for direction into how to plan injector sizes/timings for a more general understanding.

Thanks for your response

edit:

Quote:
Originally Posted by wspohn View Post
Too many people just don't understand injectors. They treat them like bigger carbs on old style engines, when in fact they are really like richer jets, not bigger carbs.

Unless you have evidence that the current injectors can't supply enough fuel for your engine, LEAVE THEM ALONE!
...but the stock LE5 fuel system is inadequate for any forced injection upgrade... or so I thought.
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post #6 of 13 (permalink) Old 11-18-2010, 07:30 AM
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Quote:
Originally Posted by idkfa View Post
...but the stock LE5 fuel system is inadequate for any forced injection upgrade... or so I thought.
You failed to mention that you were going to turbo. No injector change would be needed for any non boosted mods.

Why don't you contact DDM and give them the boost pressure you will be uising and get their opinion on what injectors will be needed. They have lots of experience with this.

Current fleet:
1957 Jamaican bodied MGA
1958 MGA Twin Cam (race car)
1962 MGA Deluxe Coupe
1971 Jensen Interceptor
2009 Pontiac Solstice GXP Coupe
2007 BMW Z4M coupe
Recently departed: 1965 Jensen CV8, 1969 Lamborghini Islero S, 1988 Pontiac Fiero GT, 1969 MGC roadster
Mods at https://www.solsticeforum.com/forum/f...thread-102178/

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Last edited by wspohn; 11-18-2010 at 02:50 PM.
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post #7 of 13 (permalink) Old 11-18-2010, 07:57 AM
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Quote:
Originally Posted by idkfa View Post
For now, it's just a simple bolt-on turbo upgrade with a garrett gt2871r. It'll be a mild tune for a daily driver until i start planing out more reliable power requirements (head studs, valves, etc). I know there have been some recommended injectors on this forum for similar sized turbos but I was really hoping for direction into how to plan injector sizes/timings for a more general understanding.

Thanks for your response

edit:



...but the stock LE5 fuel system is inadequate for any forced injection upgrade... or so I thought.
The rest of the fuel system is fine on the 2.4L up to and around 300whp. The stock injectors will fall short for you though. 42# injectors on that turbo setup should be able to get you around 270-280whp safely. If you are shooting for more than that go with some 60# injectors.

We have plug and play 42# injectors and 60# injectors we use with our kit if you need them, just give us a call.

Dave

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DDMWorks
Sales - 864-438-4949
Tech Support - 864-907-6004

WWW.DDMworks.com
[email protected]

2.4L - Stage 3 Supercharged - 305whp - 93 octane
2.4L - Rotrex Supercharged - 340whp - 93 octane
2.4L - Custom Turbo - 304whp - 93 octane
2.0L - 2871 Hybrid turbo - 371whp - 93 octane
post #8 of 13 (permalink) Old 11-18-2010, 09:51 AM Thread Starter
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Quote:
Originally Posted by wspohn View Post
You failed to mention that you were going to turb. No injector change would be needed for any non boosted mods.

Why don't you contact DDM and give them the boost pressure you will be uising and get their opinion on what injectors will be needed. They have lots of experience with this.
aww, thought that was implied by the forum



Quote:
Originally Posted by [email protected] View Post
The rest of the fuel system is fine on the 2.4L up to and around 300whp. The stock injectors will fall short for you though. 42# injectors on that turbo setup should be able to get you around 270-280whp safely. If you are shooting for more than that go with some 60# injectors.

We have plug and play 42# injectors and 60# injectors we use with our kit if you need them, just give us a call.

Dave
Thanks Dave, maybe the question was too simple. I'll be talking to you guys shortly.
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post #9 of 13 (permalink) Old 11-21-2010, 07:48 AM
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I have a set of these:

Cobalt & Ion ---> ZZ Performance

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post #10 of 13 (permalink) Old 11-21-2010, 11:30 AM Thread Starter
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Which is kinda why I asked the question the way I did. What do you really need to focus on when choosing an injector and how do you decide for things like duty cycle and flow rates rather than just an arbitrary xx#?

Figured it could help everyone out.
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post #11 of 13 (permalink) Old 11-23-2010, 12:45 AM
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The best way to size injectors is to come up with an estimate for the power you are planning to produce. From there, you can estimate a value for engine efficiency and arrive at the necessary fuel flow rate. Divide the flow rate by the number of injectors and you have an estimate for the size of injector necessary. Since you don't want to operate the injector at 100% duty cycle, you need to oversize slightly to keep the maximum duty cycle down to a reasonable number (85% is typical).

There are lots of websites with this information. Here's one: RC Fuel Injection

BSFC (Brake Specific Fuel Consumption) is a measure of engine efficiency in terms of fuel consumption per unit of power. 0.5 lb/(hp*h) is common for a naturally aspirated engine. This means in order to make 1 horsepower for 1 hour, it would take 0.5 lbs of fuel. Forced induction engine are typically higher (0.55-0.6, meaning lower efficiency) due to the increased exhaust back pressure caused by the turbo or power consumption of the supercharger.

It is also important to note that those calculations assume a certain pressure difference across the injector. When the manifold pressure is higher than ambient (boost conditions), the pressure difference across the injector would be less than before, resulting in less flow for a given duty cycle, unless the fuel pressure is increased accordingly. The opposite case happens when the manifold pressure is less than ambient (vacuum conditions). Some vehicle account for this by changing the fuel pressure. They do this by referencing the manifold pressure when regulating the fuel pressure. Other vehicles account for this in the ECU. The ECU is constantly measuring manifold pressure, and it's been given a calibration that can calculate what the change in fuel injector flow will be for a given manifold pressure. It takes that into consideration when deciding how long to hold the injectors open.
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post #12 of 13 (permalink) Old 06-16-2019, 08:52 PM
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So whats up, how is your build coming along?
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post #13 of 13 (permalink) Old 06-17-2019, 04:24 AM
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So whats up, how is your build coming along?
That last post was from 9 years ago, and he last visited the forum 8 years ago.

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