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Semi-Conventional E85 4.7 Build

Performance mods and Advanced Stroker discussion.
LRSimons
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Re: Semi-Conventional E85 4.7 Build

Postby LRSimons » October 6th, 2017, 10:22 pm

IMHO :
I woudn't go to .060" over, power gain doesn't amount to squat.
I would also get the engine together and running NA, with a fuel system built for boost on e85, first once the bugs are sorted out, add boost and a megasqurit.


I'm seeing the viability of going only .030 over with the turbo. I think i would for sure go .060 NA, but you are probably correct and adding another pound of boost would add 5x the power compared to the displacement from .030 more bore. Pointless for the extra strength/ peace of mind. The walls are thinner than I expected after I cracked the engine open for the first time, not really sure what I was expecting though.

However, I doubt the cylinder walls bored .060 would be the point of failure if the engine was tuned to the ragged edge. Which, theoretically, with forged and balanced internals, a capable fuel system, and detonation kept at bay with all the tricks- would be more power than would be realistically useful in any environment that I can think of. Besides a dyno :mrgreen:


The 35/40 hybrid was single scroll IIRC but the spool was amazing. Came on super quick; almost too quick and hard. It was not very linear, but I learned to drive around that light switch aspect of it. It was probably the must fun the car ever was. The straight 40 was twin scroll and the boost came on mitre gradually as you would imagine. Thing pulled like a freakin freight train up to. It was probably a little north of 600hp at 3.2 bar of boost.


3.2 bar??? As in ~45 psi? Holy cow... that's equivalent to somewhere around a 10 liter NA engine, right? I guess 600 or so sounds realistic when you think about it that way. :mrgreen:


Sounds promising. Forgive my ignorance on turbo matters, but are larger turbos such as these efficient/effective at low boost levels? From what I've seen people push 30+ psi on these regularly, as they were designed to do on the diesels they came on. I know large turbos will be more efficient at higher boost, running cooler and all that. But at lowish boost, say 6 lbs on this HX35, would it make sense to run this turbo? A small turbo should spool faster in theory.

Not that I'm that concerned about spool too much. High compression and the twin scroll housing will make it work whether it wants to or not :mrgreen:

A note on the twin scroll housing. Current idea is to get one of those weird twisty headers with two collectors and fab two down(up?) pipes to the turbo where a fancy flange will bolt them to the turbo. Thinking the turbo will work best on the passenger side. I know it's been done, but I have no idea if pipes will fit under the oil pan on a stock suspension jeep. Shoulda measured before the engine came out. Oh well. I'm seeing the advantage of a 2WD jeep now.

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SkylinesSuck
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Re: Semi-Conventional E85 4.7 Build

Postby SkylinesSuck » October 7th, 2017, 1:36 am

Sorry, typo. 2.2 bar! The test in the morning :)

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Re: Semi-Conventional E85 4.7 Build

Postby SkylinesSuck » October 7th, 2017, 5:36 am

K, so yeah, 2.2 bar. It was something like 33 psi or something. It was a 2.5L. Holset, just like any turbo, have an efficiency range. You can go above and below it. 6 psi will definitely be below it. These turbos were designed for relatively high boost applications on diesels. IIRC the HX40 compressor didn't start making good power until like 1.2-1.3 bar, and I think the HX35 was similar. If you aren't running that much boost, you might have yourself the wrong turbo. Then again, what are your power and driving goals for it?


I like the idea of staying with a split exhaust going in to each exh housing scroll. Is the firing order of our beloved I6 conducive to feed one scroll 1-2-3 and the other 4-5-6?

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Re: Semi-Conventional E85 4.7 Build

Postby SkylinesSuck » October 7th, 2017, 5:45 am

I just reread your above post. The efficiency at higher boost means airflow vs heat. It will still get hotter as you add more boost. Less boost means a much cooler charge, but also much less air flow. There is a balance. You could run it at 6psi, but it wouldn't make a lot of power, and wouldn't spool as well as a smaller turbo and/or one optimized to run at lower boost. Don't grey stuck on running certain boost numbers though. Lots of people don't have a good understanding of air flow vs boost. 14 psi on "x" engine with "x" turbo does not equal to 14 psi on a different set up. The same applies for different turbos/blowers on the same exact engine at the same boost.

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Re: Semi-Conventional E85 4.7 Build

Postby LRSimons » October 7th, 2017, 10:28 am

I like the idea of staying with a split exhaust going in to each exh housing scroll. Is the firing order of our beloved I6 conducive to feed one scroll 1-2-3 and the other 4-5-6?


Yes. From what I've read, setting up a twin scroll is (more) convenient on an i6 as the optimal combo of cylinders is 123-456.

As I was walking past the factory header(ish) sitting in my driveway waiting to either go out with the trash or get picked up for free, I noticed this-



That's pretty much what I would be looking for in the cool twisty header- ports 123 and 456 combined into individual pipes. Sure the runners aren't equal length and it probably flows crappy, buuuut it's an easy solution and saves some money.


I just reread your above post. The efficiency at higher boost means airflow vs heat. It will still get hotter as you add more boost. Less boost means a much cooler charge, but also much less air flow. There is a balance. You could run it at 6psi, but it wouldn't make a lot of power, and wouldn't spool as well as a smaller turbo and/or one optimized to run at lower boost. Don't grey stuck on running certain boost numbers though. Lots of people don't have a good understanding of air flow vs boost. 14 psi on "x" engine with "x" turbo does not equal to 14 psi on a different set up. The same applies for different turbos/blowers on the same exact engine at the same boost.


Agreed on the cfm vs psi point. I think I understand the theory, but with no actual experience it's difficult for me to wrap my mind around.

K, so yeah, 2.2 bar. It was something like 33 psi or something. It was a 2.5L. Holset, just like any turbo, have an efficiency range. You can go above and below it. 6 psi will definitely be below it. These turbos were designed for relatively high boost applications on diesels. IIRC the HX40 compressor didn't start making good power until like 1.2-1.3 bar, and I think the HX35 was similar. If you aren't running that much boost, you might have yourself the wrong turbo. Then again, what are your power and driving goals for it?


This was the "effectiveness" window I was asking about. Not making good power until 1.2 bar might not work that well for this engine. How would displacement affect this?

Power and driving goals? Hmmm... I guess a healthy amount of reliable, controllable power in a unique format would be what I'm looking for. And being able to beat the redneck lifted truck crowd and the rich kid ricer crowd stoplight to stoplight.

I think I just described a regular Jeep stroker motor. :lol:

Power goal? I may as well pick a number. If 200 at the wheels is about what a "normal" stroker makes, a breathed on stroker at 1 bar of boost *should* make about double that. Let's shoot for 350 whp. Should be enough to break some driveline components :mrgreen:

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Re: Semi-Conventional E85 4.7 Build

Postby LRSimons » October 7th, 2017, 10:34 am

Forgot to attach pic of the factory exhaust.

Image

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Re: Semi-Conventional E85 4.7 Build

Postby SkylinesSuck » October 8th, 2017, 8:47 am

350whp is no small goal for our vehicles. Did you say it was 2wd though? Anyways, I'd say 1.2-1.5 would be what you need on that turn to get those kind of numbers with that turbo. Just tune it right and intercool it. Maybe a little meth for a safety margin.

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Re: Semi-Conventional E85 4.7 Build

Postby LRSimons » October 9th, 2017, 5:05 pm

Negative on the 2wd, I was remarking on how much easier that would make things :D

Intercooler tubing will probably have to down the sides of the radiator and underneath. Not enough room on the sides to go straight past. That's a long way off though. Cross that bridge when it gets here.



Cut off the end of the stock manifold- The tubes are D-shaped rather than circular. Have a look. Turbo flange for comparison.

Image

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Re: Semi-Conventional E85 4.7 Build

Postby LRSimons » October 11th, 2017, 6:09 pm

Ordering parts. Would the Comp 68-232-4 be a bad cam choice for any reason? I think it sounds like a good compromise between stock and crazy as I stated a while back.

Just want to make sure I get any relevant opinions before I hit the button.


Also, has anyone used an oil pump rebuild kit? The price is right and it's not like the housing itself is going to wear out...

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Re: Semi-Conventional E85 4.7 Build

Postby Russ Pottenger » October 11th, 2017, 11:01 pm

Are you doing a valve spring upgrade?

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Re: Semi-Conventional E85 4.7 Build

Postby LRSimons » October 12th, 2017, 1:23 pm

From what I've heard a valve spring upgrade is necessary for this cam.

From what I've read, a lower spring pressure might work with significantly lighter than stock valves. I have not found any but haven't looked that hard.

So, yes to stiffer springs.

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Re: Semi-Conventional E85 4.7 Build

Postby Russ Pottenger » October 13th, 2017, 9:57 am

LRSimons wrote:From what I've heard a valve spring upgrade is necessary for this cam.

From what I've read, a lower spring pressure might work with significantly lighter than stock valves. I have not found any but haven't looked that hard.

So, yes to stiffer springs.


The most important issue is the valve spring relationship to lift and coil bind.

Just wanted you to be aware that Comp's 68-232-4 cam is right at the limit of a stock spring.


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