With my apparently blown motor, I’d like to do an NA build. I’m a big fan of high compression. The highest shelf pistons seem to be 11:1, but it seems this motor should be able to safely run higher than that on premium pump gas. I don’t want to get crazy high or run race gas, but I would like to take advantage of “free HP”. What have others safely run? Obviously cam choice and other factors will come into play, but just looking for a general idea. I would think that 11:1 pistons, block decking, and head decking will end up with roughly 11.5:1, but would really like to be closer to 12:1. Anyone have experience in this area? Thanks!

 

I wouldn't go higher than 11:1 on premium pump gas unless you were changing cams. But for the cost of all that you could be into the low end of some kind of FI so...

 

I seem to read that a lot of people say you could be into FI for that price. I just can’t see how that’s feasible. If the bottom end has to be built, it’s going to be the same price whether you go NA or FI, but then you now have the immense expense and added complexity of the turbo kit. I would just rather do an NA build, I want the immediate throttle response and low end torque of an NA build, and feel it would be better for autocross and track use. I haven’t decided on what exact cams, but will do cams.

 

Well the bottom end doesn't HAVE to be built if you are ok with 400whp. A used Vortech supercharger system can be found for around $2500 and an Uprev tune for another $700 or so.

That can be used on a completely stock motor and is hands down the best WHP per dollar spent. 100+whp for $3k or so.

Cams alone are like $2k and will gain you maybe 25whp and you still need a tune

 

An SC would be sweet, but I have yet to see a used one pop up for sale. And I know it doesn’t HAVE to be built to add FI, but my bottom end is toast, so in my case, I do have to build the bottom end. And yes, I know I could throw a junkyard motor in, but I’m not going to, I don’t want to throw another used oil burning motor in. I want a solid bottom end with a good oil pump and rings that keep me from looking like I have a diesel under the hood lol!

been looking at Tomei cams (under $1K), and even JWT cams (a little over $1K). I plan to rev the motor, so I would do springs either way. With porting, high compression, cams, and some other bobbles and bolt ons, should be possible to get close to 400 engine HP which should be plenty fun and more than enough for autoX.

 

If it’s VQ35DE OR HR related, it’s probably been done. I think I’ve seen 3-5 high compression builds and they won’t even make 400whp 😅.

just rebuild the bottom end with Z1’s low compression power pack and keep an ebay search open. They do pop up.

 

I certainly don’t think I would ever come close to 400 whp, in fact, my “close to 400 engine HP” is probably very optimistic as well. I want to build this motor to be fun, reliable, streetable, and torquey enough for track use. I don’t want a high HP build, and I definitely don’t want to put $3-5k into FI, whether turbo or SC. I love power, but that’s not what this build is about. I just want a snappy, ultra responsive motor that will pull hard out of corners and rev to 7500 rpm all day long. If anybody here tracks their car, you know what I mean, the high HP cars are the ones that usually are in the pits with issues or are off in the grass in a cloud of dust.

My other goal is to have this motor in and the car driving before the end of the season. That may not be attainable especially with how long machine shops tend to take, but I don’t want this thing sitting taking up garage space while hoping for a used SC to pop up. I can always add power in the future. I just need to get this motor put together in a reasonable amount of time for a reasonable amount of money. I know, famous last words 😂.

I did a search, and there has been only one SC on eBay in the past 6 months and it was almost $4k.

So my plan is to do a nice high compression build. I have seen a couple in the 12.5:1 range, but they are running race gas. E85 is plentiful around me, could a guy get away with 12:1 on an E85 tune on a VQ35DE?

 

I think the hard limit on the DE stock compression was almost an even 300whp, that's with cams.

The Nismo tuners were hitting almost 350 but that was running like 8k and 13:1 I think.

Cutting bigger valves, upgraded springs, upgraded cams. That's almost the cost of a supercharger, thus why the high hp NA builds were mercifully few and far between. However if that's what you want then absolutely go for it.

There's been a couple ITB builds that made some CRAZY power but you're running a sump (and ITB's...) at that point so... not affordable at all.

Sasha with Onpoint made over 500whp out of an NA HR engine, no one talked ****.

As for the e85 question, you could do 13:1 on e85 but again it's mostly a cost issue. You're replacing the ENTIRE fuel system due to the other issues with e85, plus using 15%-20% more fuel for normal driving just due to the nature of ethanol. For a... maybe 10whp gain NA it's typically not worth the cost. 13:1 NEEDS big cams too.

Do do a little research on the matter look up "effective compression ratio" and how it relates to boost. Basically taking an engine with 8:1 compression and adding 20 lbs of boost is essentially the same compression as the same engine NA running at 16:1 or so compression ratio.

(EDIT) boosted, the lower the compression, the higher the volumetric efficiency, but the lower the thermal efficiency. 7:1 starts very low but makes steep gains with rpm (boost). 8.5:1 starts a little low but makes moderate gains at higher rpm (compared to the same boost).

This is why you typically don't boost higher compression engines, the steep loss of thermal efficiency absolutely KILLS the performance gains you COULD be making at higher rpm (i.e. higher boost).

Now with NA you have essentially the same thing. Higher compression (regardless whether from native compression or from boost) means higher volumetric efficiency but lower thermal efficiency. There's a breakpoint of around 13:1 where you're losing so much thermal efficiency for minimal volumetric efficiency that is ok for a racecar, but it's not going to be very streetable.

 

I see catted DEs with stock bottom ends making right at or over 300 without cams regularly. Regardless, I have no intention of chasing numbers or hitting a certain number goal. Again, my plans are a fun, responsive motor that is reliable, especially on the track.

I haven’t talked to my head guy yet, but will see what size valves to go with. I will be doing springs. I don’t want to lose VE with huge ports and big valves. I want to maintain a strong bottom end for coming out of tight corners, like everything, gotta find a nice balance. Proper porting should help with VE and help with power.

I see you keep mentioning “high hp NA” builds, but again, that’s not what I’m going for. If I wanted high HP, I would plan a high HP build, but I am planning a strong, reliable, motor build. Whatever it makes, it makes. I don’t want or need high HP for autocross.

I have been building motors for quite awhile. I am very big into efficiency. Tightening up squish, decking heads for more compression while using lighter pistons, longer rods for better ratios, custom stroke cranks, reduced pin diameters for lighter weight, etc. And while it is good to look at numbers and what is most efficient, it is easy to lose the goal of a responsive motor that works for your intended usage. Yes, I could make a more efficient motor by boosting it, but even if it’s the most efficient motor ever built, does that mean it’s a good build? Not if I want zero lag, less power, and a motor that works for my intended usage. Not to mention I want to hear that VQ sing.

I am into Powersports, and I’ve had one of the “top shops” tell me that over 12:1 on my particular motor was dangerous and not recommended, especially with the big bore and stroker that I was planning. Well, I built that motor, ran 14.25:1 compression and it was the most fantastic build I ever have had, no heat issues, no problems and it ran wonderfully. The moral of that? Sometimes people get scared and the “numbers” say it shouldn’t be done, so they never try it, and they miss out.

I really appreciate all your help and posts, and I enjoy the discussions. But I do wonder what SC kits you are looking at. You mentioned that the price of bigger valves, springs, and cams was close to the cost of a SC, if I could get a new SC for $2500 then yeah, I may consider it, but all the kits I see are $6-$7k, that’s 3 times the cost of valves, springs, cams.

 

To be fair most of us are comparing used tuner kits to new NA build parts for prices, which isn’t really fair. If you want an NA build, do it for sure. I’ll be excited to see your progress!