Building a Stroker LQ1

[joelbob]

Hello all.

I think 'I've been dormant for more than a year now. Some of you may remember me. - I'm the guy who sold the full set of new internals for an HM284 a couple of years ago. I had acquired them from Getrag Gears in NC shortly before they scrapped the parts they had left. Coy (one of the rebuilders that worked on the transaxles when GM still had their dealer rebuild / exchange program ) told me that they scrapped enough parts (management told them "to make room") to rebuild a couple of transaxles. Great! 'Way to treat such rare parts (trying to swallow puke)! It sticks in my mind that the purchaser was a member of this group. If so, shoot me a message and let me know what you ended up doing with them.

I've finally commited to building a stroker LQ1. I've been half-heartedly acquiring parts for several years now. In all honesty, I'm not adding much stroke. Just enough to allow the use of off-the-shelf parts. The reciprocating assembly is a hybrid combination of an offset ground 3500 steel crank, 5.850" modular Ford stroker rods and '93-'99 NorthStar slugs with floating pins. Final stroke will be determined after the block is machined and I have the new rods to mock up with the stock crank. Preliminarily, I have estimated displacement to be around 3.6L. I say preliminarily because I am not sure where the stroke will end up after the block is squared and calculations are made for optimum quench. It looks like the stroke is going to wind up being around 3.44" The donor engine is an 80k mile unit out of a rolled '96 Z-34.

Necessarily, with the stroke and compression, I am planning on an N/A build. I am going to have Joe Bray at American Custom Cams analyze and regrind the cams once I have a definite figure on compression. Speaking of compression, unless I do some modification to the combustion chambers, the bore / stroke combination is going to yield around 11.2:1. It might make sense to use a pair of earlier heads to get around this. I really don't want much over 10.5:1. At the same time, dont want to give up stroke or sacrifice optimum squish / quench. I guess I'll get the block machined and then address the challenge when I know what I'm dealing with.

Once the cams are ground and I have an idea of powerband, I will be able to calculate optimum intake runner length / volume for ram effect timing. This will allow me to build a performance matched upper intake.

Lastly, I plan on making a set of 180 degree anti-reversion headers. AR cones almost seem redundant on a 180 degree design but I have been aching to make a set of AR headers since first learning about the design theory. I've had a set of '96-'97 flanges for about 3 years now and they are just begging to be used.

The vehicle this is going into is a 1996 Z-24. I was fortunate enough to land one of the surplus 3.94 fdr NVG transaxles that have been floating about. I need to get the case half swapped for use with the LQ1. Right now it is setup for a Quad-4.

This is a winter project so it'll be a little while before I get rolling on it. Right now I am trying to finish up work on my M35A2C so that I can get it sold.

Feel free to add comments / questions. I hesitated making the post because I understand the disproportionate ratio of theory / daydream and accomplishment when it comes to things like this. In spite of that, I thought some of you might enjoy hearing about my project. Fortunately for me, I own a decent assortment of full-sized conventional machinery to make such things possible.

~Cheers

[SappySE107]

11.2:1 shouldn't be too bad if you can get the appropriate regrind and time it. In fact, you should consider making some of those timing tools you told me about, as there is a decent demand for those, myself included. I know the pushrods can take 11.5:1 and even 12.5:1 on pump gas so I would not worry too much about those. Perhaps some ARP head studs for insurance but it would be awesome to hit that compression.

I didn't know you had a 3rd gen J body. When you get rolling on this, I would like to come check out the engine bay without the motor as well as your header design. I don't believe you will need to deal with the AR either but it shouldn't hurt.

Perhaps I will be motivated at some point during the winter to take some port molds and determine the specs needed to fill out dynomation for the 3.4 DOHC. This would be useful for header lengths and cam specs based on the other modifications you plan on making. Biggest issue will be making another valvetrain tool for the flowbench, but I bet you could make one of those no problem. I need numbers with the manifolds in place to have a useful simulation setup.

[robertisaar]

this sounds like the start of a very bad-ass 660...... in a lightweight, tiny car no less...

[pocket-rocket]

I can't wait to see the finished product. I think that thing is going to rock (if it can get traction, lol). Might have to put wheelie bars on it.

[jman093]

Wow, looking forward to that build

[joelbob]

Well, FedEx surprised me and dropped off my NorthStar pistons today. They look great and don't appear to have any shipping rash. The posted specs on the pin were correct. - It measures .866". It is offset approximately .060". 'Anybody know what the stock LQ1 offset is? As soon as I get time I'll post some photos.

[joelbob]

Ben, I'm with you on the cam timing tools. For those who didn't see the photos I posted a couple of years ago, here is a link to the thread: http://60degreev6.com/forum/f101/fir...-effort-t36225 . The set I made was fairly straightforward because they had an equal angle in both cam positions. With grease on the ramps, the primary bar was pulled into a position parallel to the top of the cam carriers when clamped down. This is critical because the primary bar is the reference for angular settings. (The goal here is to perform advance / retard adjustments at the cam with the crank at TDC. This makes in-chassis adjustments a little less cumbersome than the crank rotation / estimate method.) A challenge presents itself with differing cam angles because the primary bar will not automatically "seek" a zero angle position when clamped down. The best design for adjustable cam tools is one that involves contact with the top surface of the cam carrier for a zero angle reference. The next type I machine will consist of a dual trunion type primary bar having two equal radii concentric with the cam bores. This will allow a pair of semicircular angle blocks (think half circles with flats contacting the cam flats) to sit in the trunions for angular adjustment. The equal sized trunions would eliminate the tendency of the primary bar to rock. - Contact with the top surface of the cam box will insure a zero primary bar angle. One benefit of this design is that it is relatively low profile and shouldn't present any on-vehicle clearance issues. Anyone else given thought to optimum cam tool design?

[SappySE107]

Other than using steel and not aluminum for the tool, I am not a machinist or a tool designer:P I know the old tools that were available wore on the cam flat locations and I was told they were not accurate past 0*.

Either rotating adjustable like you explained, or a replacable flat with the angle already ground would be ideal. Personally, I only want want 6/6 timing for my cars, but adjustability and experimentation would be worth it to a lot of people I am sure.

[joelbob]

Well, I had a few minutes so I snapped some photos of my NorthStar pistons. I checked the compression height and confirmed that the posted spec is correct at 1.250". I also weighed one of the pistons and found it to be 514.5g with the wrist pin and a couple of locks. The rods I plan to use have an advertised weight of 592g +/-. 'Anybody have approximate weight specs for the LQ1 rods and pistons?

[pocket-rocket]

I know Ben has some pistons/rods at his house. If he needs it, I have a hydraulic press to remove the pistons from the rods to get a weight on them individually. Then again, you probably have one as well, as does the machine shop he uses... Aren't new pistons a thing of beauty?

[OldSkoolGP]

Now that I've owned a DOHC and seen what can be done with the Gen III pushrod engines, I think I can finally say that the 3.4DOHC, while an amazing engine, is not the best way to go for an N/A buildup. It's too big, too heavy, and holds in too much heat. Parts get scarcer every day and they're expensive compared to pushrod parts. I think you could make just as much power with a Gen III 3500 build, but maybe I'm wrong. Hopefully I am. It would certainly justify what I had saying for the past 9 years.

[no_doz]

im sure the 3400 has more potential but its at much more cost/much more fabrication since just about everything needs to be custom due to no real aftermarket for them. its so sad, just imagine if GM would've ran with the design, upgraded it & fixed flaws-& stuck them in many more vehicles... 90* v6's would bow down.

out of curiosity is the shortstar a much better design than the LQ1? i love the whole timing chain thing but otherwise is it really any better considering a lack of after market?

[robertisaar]

90* v6's would bow down.

out of curiosity is the shortstar a much better design than the LQ1? i love the whole timing chain thing but otherwise is it really any better considering a lack of after market?

90*V6 DOES bow down: they are no longer produced, and were replaced by 660s


BTW: the shortstar is NOT a 660: it is a 690

[no_doz]

90*V6 DOES bow down: they are no longer produced, and were replaced by 660s


BTW: the shortstar is NOT a 660: it is a 690

i know this-are there any drastic improvements from the lq1 to the shortstar other than timing chain?

[joelbob]

OldSkool, I hear you on the size, weight and parts availability issues. I also agree that some impressive hp numbers are being had from stock (let alone modified) pushrod engines. My love for the LQ comes from the 4-valve design and the flow capabilities of the stock heads. (As a side note, almost nothing sounds as good as a 4-valve 6cyl. - Particularly mid-engined cars with short exhaust.) GM really went limp on things like cams, tuning and intake / exhaust. The timing drive could certainly have been better too. At least its not like my boss' Ferrari 355 Spyder. - I think that a timing belt replacement with a tuneup is around $14k. The other part of the equation is that this build will put an end to my speculation regarding the potential of the LQ. Other than the process specific machines to do block boring, crank and cam work, etc., I own all the equipment needed to make the "one-off" pieces I need. - This should keep the cost down.

no doz, I don't know much about the ShortStar. I am not sure how it stacks up in terms of valve size and port configuration. I like the timing drive but I doubt that it is as adjustable as the LQ in stock form. I do like the idea of the all aluminum design. I suspect that it might face some of the same head bolt challenges as the NorthStar. (GM didn't thread insert the block.) 'Also not sure about crank journal size and crank interchangability with other engines.

In summary, I just have an infatuation with the LQ. It makes sense for me to build it since I have a good engine core, a 3500 crank and many other new parts for the engine. The whole intimidation factor surrounding working on the LQ just adds to the mix. - I guess I like to do things the hard way :-).