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Stroker cranks for the 5.4 mod motor

79K views 244 replies 25 participants last post by  phillyc 
#1 ·
After seeing the results of the 2014 Engine Masters Championship I decided to email Sonny Bryant cranks to find out how much one of their full internally balanced billet 4.700" stroker cranks cost. I thought it may be a cheaper option for more cubes to the traditional big bore block / stock stroke 358ci.

With a stock 3.552/3.572 bore you'd end up with 373ci/377ci and the 3.700 bore a huge 404ci.

The billet Bryant crank ended up cheaper than I thought at $3100 plus Mallory plus freight. They do not supply rods, bearings or pistons and rings. I'd reckon on $5500 all up for the assembly.

Compared to stock stroke rotating assembly with comparable component specs which would be about $3000, it's probably $2500 extra.

Compared to the other 4.380/4.415" stroker kits. Eg A billet Brian Crower BC0428/BC0429 at $3900/4500 USD the total cost would seem when compared like for like only about an additional $1000 extra.

Powerheads have a 377ci (6.2L) SHM alloy big bore block with 4.415" stroker crank - shortblock for $8995 USD. Get the advantage of a 50kg weight saving and extra cubes. I emailed them about using a 4.700" crank and they said they would have durability concerns.

What sort of machining work would be required to be able to fit a 4.700" cranks / rotating assembly? Either to an Iron 5.4 block or 2013 GT500 alloy PTWA block?

Would there be durability concerns for a 4.700" stroker crank engine? If so, life expectancy? Max safe rpm for street use? About 6500rpm? I believe Jon Kaase did over 800hp with a Sullivan in testing at 7200rpm.
 
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#2 ·
Jon didn't have any problems putting the big stroke in his aluminum block, but I can't say it wouldn't be the same for an iron block. As for durability concerns, as long as good parts are used and the machine work is good the engine should work great and last a long time. Knowing your combo I thinks it's safe to assume that it would rarely see 7000rpm.
 
#3 ·
Thanks for the reply NA SVT. Yeah, it wouldn't see 7000rpm often. Be nice to be able to do it though :) I'm more interested in big torque and a wide spread. Most use would be 1500-3500rpm. It's my 4100lb 6M daily driver and only gets open track and drag meet use a few times a year.

If I was to do it and go the whole hog, I think the build would be done in two halves with a 4.700 stroker rotating assembly with cams being the first half and then doing ported and big valve heads later on. I don't think I could justify the alloy block as sweet as it would be.

From what i've read, it seems the maximum compression on pump fuel is about 11-11.5:1 for pump. On E85 could go about 13-13.5:1, but although it's sold nearby to me, there just isn't enough stations to be completely practical.

With a 11.5 ratio and stock 03/04 heads (268 cfm) as fitted to my Aussie Boss 260, suitable cams and 377ci what sort of power and torque would be expected? Would 450hp/450tq atw @ 5500/4000rpm be reasonable guestimates?
 
#4 ·
With a 11.5 ratio and stock 03/04 heads (268 cfm) as fitted to my Aussie Boss 260, suitable cams and 377ci what sort of power and torque would be expected? Would 450hp/450tq atw @ 5500/4000rpm be reasonable guestimates?
525rwhp/450rwtq, average hp and tq numbers from 300-6500 would probably be in the 450/425 range, they would be higher if you were okay with rough idle.
 
#8 ·
Here's a pic showing the crankcase of the GT block Jon used
That is a great picture. Excellent detail. I'd imagine similar clearancing work (depending on shape) is required on an Iron 5.4 block (my most likely option) or the 2013 GT500 alloy PTWA 5.8L big bore block.
Thanks for sharing (you and Jon K). :)

Just curious, looks hand clearanced with a die grinder. Was it done by hand / similar or done in a mill?
 
#10 ·
Thanks Jon! This is what is great about forums :) A legend engine builder answering my humble questions. Todd you're pretty cool too!

Do we have an idea when the article from PHR magazine on the winning EMC Mod motor build is coming out?
 
#11 ·
Well i'm now going ahead with a 4V stroker 5.4 based engine. I'm using offset grinding from a Ford 2.086 rod journal down to a Honda 1.888 journal. It will end up with about 349ci with a 3.572" bore and between a 4.340 to 4.350 stroke. I've bought myself a suitable set of 6.560 long H beam rods with a Honda journal. AFAIK i'm going to be the first anywhere doing this combo! :cool:

I'd like to say a BIG thanks to NA SVT for all his advice and answering all my questions.
 
#15 ·
If my math is correct the piston CD will need to be 1.24 to achieve a "near" zero deck height. That is only .020" higher than stock which is 1.22". Regarding quench, the 4v chamber is quite efficient and therefore needs little to no quench to be effective.


  • Stroke
    4.350
  • Crank throw
    2.175
  • Con rod Length
    6.658
  • Compression height
    1.250
  • Deck height
    10.079
  • Piston to deck
    -0.003
 
#16 ·
Ahhhh.. thank you na svt! I figured incorrectly. ...image that..

Anyhow his as of now compression center pin height for zero deck is 1.340"ish

Throw~2.175
connecting rod~6.560
Comp. Height ~ 1.347
Deck height = 10.079

I missed read his post too...lol


Anyhow piston pin to zero deck is 1.347ish and if I was this guy I would cam it hard with a zero deck piston and adjusting the compression with the piston dish.your piston speed is going to be nuts!! But ....pre ignition gets beneficial at high rpms with a high piston speed. With that said look into a compression of 14.+
 
#20 ·
Thanks. Will keep the updates coming as they happen.

Still having a struggle to get well priced pistons. It's just a shame that I can't find an off the shelf piston with all 3 traits.
* 0.927 pin size,
* 1.34 compression height
* Ford Modular bore size.

There are several examples of each with 2 of the specs, but not all 3. If ANYONE knows of an off the shelf piston fitting the 3 specs, let me know in here or via PM :)
 
#22 ·
Thanks for the link. It's much appreciated :) What your suggesting is a good idea. I had wondered whether it was feasible a week or two back. But, got so busy on trying to find suitable pistons, that I kind of forgot about exploring that option.

Most likely if I don't go with a custom piston, then the Eagle rods I have chosen will need to have the Pin End machined down from 1.000" to the standard Ford Mod 0.900" width. This will add some cost. Perhaps a resizing could be done on the rods at the same time. Might check with my machinist on likely costs.

PS reading that Kaase EMC article was good too. He used the same series of rods I have chosen although Jon used stock 6.657" length.
 
#25 ·
Thanks for those. Suggestions are welcome! Yeah, both have 0.866 wrist pins and are made for the standard Ford modular 0.900" Pin End width. I am waiting on a price back from MHS though for custom Diamond pistons.

Actually reckon the Probe SRS would make a good piston for a mild performance rebuild. It has 1.320 compression height. Which would leave it 0.019 in the hole. So, most likely it could get away with it's lack of valve reliefs! NA SVT I know it's normally true zero deck that have issues. But what camshaft duration and lift with an intake ICL of 108 could be fitted and avoid piston to valve interference with the piston 0.019 in the hole?

Thanks!
 
#26 ·
I haven't had a chance to talk to my machinist. So, just clarify that this would mean the original needs to be pressed out and these then pressed in?

If I can't get the custom pistons at a decent price, then getting the PE width resized and rebushed is my next option. Thanks for the heads up on cost.
 
#32 ·
I'm sticking with the 5.4 iron block that I've got and making 349ci out of it. This will be done by boring out 20 thou to 3.572" (to allow for future boost if I desire), and the stroke will come out at 4.340 to 4.350 depending on tool wastage, current surface quality of the crank journals etc.

5.8 alloy blocks are awesome, BUT still really expensive. No cars were sold in Aus with that block fitted. The cheapest is the PTWA (spray bore) 5.8L block from the current GT500. These are $3899 USD from MMR. Add shipping, taxes, custom fees and the AUD/USD conversion rate of 88c then it quickly becomes $6000 AUD. :barf: I project my ENTIRE build will be $8000 AUD or so.

Add the alloy block cost & it is more money than I could justify or let alone have! I reckon it'd be $13500 AUD. However it would get me to 374ci with my proposed stroke. ~$131/ci

In fact, I'd probably do a 4.700" stroke Bryant billet crank in an iron block before that option and bore it 3.592" which would net 381ci :) That option would come up at about $11500 AUD. ~ $83/ci

As you can see, doing it my way with reusing the stock 5.4 iron block and an offset ground crank allows for a nice increase in cubes, with a moderate price premium of probably about $750 AUD over a stock capacity built 5.4 4V. ~$39/ci,
 
#33 ·
Yeah, makes sense. You are really building that thing cheap (price-wise). That is awesome. You've obviously thought it all out and have picked some nice parts. It should rock!
 
#34 ·
Yeah, I have to. Research takes time, but costs very little. Sure it'd be nice to have even more cubes added. But, until someone releases a $2000 alloy 5.8 block.... really this is the most cost effective I could do it. Thanks for the encouragement :)
 
#35 ·
question and apologize for the ignorance. But assuming Powerheads would sell the stroker crank only, for someone doing a very mild street car with more cubes and torque:

Stroker crank
.020" overbore to clean up the block
MMR forged 5.4 rods
Forged flat top pistons ( MMR economy or something)
Shave the heads .030"
Mains/rod bearings/etc
JBA 3/4 headers
Comp 106100 or Crower cams
Coyote/Boss 302 intake w/adapter plates

nothing fancy, just a shade to the side of bare bones. Would 400+ rwhp be reasonable?
 
#38 ·
If a stroker crank (increase of 19ci) is added to a 4.6 it will gain about 20/20 given the same compression and cams. Adding 27ci to a 5.4 should increase power by at least that much and if the cam profile is changed to take advantage of the extra cubes the gains should be much greater.
 
#45 ·
Yes, I've referenced that write-up before. Some nice info in it (but a little out-dated as far as the Cobra R/FordGT/GT-500 heads are concerned). I guess for a moderate increase in displacement like you are doing, the '03/'04's are the best option considering the intakes available. I guess for a monster cube engine like Jon Kaase's, maybe a larger port 5.4L head (FordGT or Navi) would be better suited.
 
#46 ·
Yes, I've referenced that write-up before. Some nice info in it (but a little out-dated as far as the Cobra R/FordGT/GT-500 heads are concerned). I guess for a moderate increase in displacement like you are doing, the '03/'04's are the best option considering the intakes available. I guess for a monster cube engine like Jon Kaase's, maybe a larger port 5.4L head (FordGT or Navi) would be better suited.
Yes, a little outdated as it misses those newer heads.

Yes the 03/04 are the best for my situation and i'm sure would be for most people. It's all about getting the headflow and intake port volume matched to the application. At 295-305cfm, the heads will theoretically flow 600-625hp worth of air. I'm looking for about 550hp at the motor. So, a really good match. Actually the end custom porting cfm figure will depend on the discussion I have with the porter beforehand. It will be pretty much predetermined off how I want the power delivery and how much power i'm chasing.

My porter Jake, has had a customers 4.6 on E85 make 680hp at the flywheel on the engine dyno.

The GT heads on Jon Kaase flowed 'something' like 370+cfm so were theoretically rated at 760-780hp. In testing he did 800hp on a Sullivan though!
 
#47 ·
In my AFF thread, I had someone ask me whether I had considered a welded / built up crank to allow an offset grind using stock sized big end bearings. I must admit, I did not consider this option previously.

What are peoples thoughts or opinions on welded / built up cranks?What is the typical offset achieved with a welded / built-up crank?

I'm still keen to proceed on my current course the way I am with an offset ground crank. Purely on cost competitiveness.

I imagine if I combined both techniques of reduced big end bearing size and welded crank that the gains could be pretty decent! Obviously at a fair cost. The oil holes will need to be re-done, plus the cost of the welding, plus the cost of the offset grind.
 
#49 ·
Thanks for your reassurance. I spoke to my engine machine shop today and they aren't keen on welding / building up a crank. Concerned it would affect the metallurgy of the forged crank. Eventually leading to fatigue. They believe it's a practice best left in the past...

I'm curious still about the available stroke increase afforded by this technique, but very much unlikely to proceed with it.

Todd, what sort of increase in stroke could typically be made using the welding technique?
 
#51 ·
Just for curiosity as much as anything, I've asked about Darton 700-120 MID sleeves to suit the Ford Mod iron 5.4 and machining costs here in Aus. Been quoted $2-2.5k AUD to fit them plus the cost of the sleeves themselves.



Darton Sleeves

What sort of cost to fit them in the US?
 
#52 ·
Not sure about the price, but I can ask the local shop that I'm interning at on Monday and see. Also, I found these sleeves online that are less than the Darton MIDs and look to be dry sleeves, so there's probably less labor costs. But at this price I'm not too sure about the quality of the product. However, the bore is 3.660" which just happens to be the same bore as a Coyote .030" over, so that could save you some money on pistons (vs buying customs). :salute:

LA Sleeve BLOCK SLEEVE 3.660 BORE SUIT FORD 5.4L MODULAR V8 LA-3822 - LA Sleeve
 
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