High Compression Del Slo Questions (build starting within a month)

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Squishyxout

New Member
Alright guys/gals, I've had this del sol for about a year now (1995 Si) so far, everything is stock beyond legitimate suspension upgrades and adjustable parts so I can actually have a proper alignment, because well, I'm not a huge fan of buying new tires all the damn time. I love the little thing, it's peppy, it is reliable as hell, it's different, but still a lego honda lol. I want a bit more power out of it and I don't want to go with boost. Boost complicates things, greatly reduces reliability, and as a wise man once told me "Keep it simple, stupid". I'm really only looking to achieve about 170-180 Hp. I'm not swapping in a motor, as that would entail just as much, if not more, work than boosting, not to mention the fact that Del Sols have weird shift linkages vs civics. This thread is going to be all about performance, I'll probably post a thread about the cosmetics at a later time.

First things first, It's a stock z6 with ~260k on it. I know that it's not Ideal, but before I buy parts, I'm going to have it tested with magical sonar beams to make sure there's no cracks or warping in the block or head. Assuming that it comes back all well and good, I'm going to start a high compression build using some of the following:

There are 2 possible piston choices I'm considering; PG6 Pistons or P29 pistons. I have questions about both setups.
Part/Compression change (static compression)
PG6 pistons in a z6 block 9.14->11.67:1 (so 11.67:1 is going to be our new control comp ratio for these pistons)
Stock Head Gasket to B7 .048" HG 11.67->11.33:1
Stock to Cometic .018" HG 11.67->12.32:1

P29 pistons in a z6 block 9.14->12.05:1 (12.05 is now our control here)
Stock HG to B7 HG 12.05->11.69:1
Stock HG to Y8 2-layer .025" HG 12.05->12.48:1

Okay so now the billion questions
First, I've heard before that the PG6 pistons limit your cam choice as the dome sits too close to the valves at TDC. If I run these pistons, is it safe to run a stage one Comp Cams camshaft?

If I were to go with the p29 pistons and go as High compression as I can (y8 .025) would I be fine if I had to settle for 91 octane gas somewhere in the boonies? Additionally, would the car still be streetable at 12.5:1? Same question on the Comp Cams Stage 1.

At what point do I have to upgrade my injectors? I already intend to upgrade to a 255 lph Walbro fuel pump (personal preference and I have extensive experience with this fuel pump), but injectors are quite pricey, so if I can use these I'd be pretty happy: http://www.ebay.com/itm/NEW-440cc-F...ash=item28238a556f:g:ozwAAOSw3KFWeL8Y&vxp=mtr

I know everyone is all gung-ho about Skunk2 products, but I'm still recovering from my GM days, and I've had great luck with Edelbrock, so that's my first choice on intake, I've also seen some OBX intakes with GIGANTIC plenums and straight runners, but they're for the obd2 d16's, can I adapt this easily? any opinions on performance??? And I am going to match the TB to the intake.

Exhaust isn't that important to me, I'm honestly going to buy an ebay 4-1 mani/downpipe with a test pipe (yay Iowa for no smog tests), and a 2.5" cat back, hopefully a twin-loop muffler (depends on the sound, I don't like fart cans or the lawn mower esque sounds they produce) Also considering a custom exhaust similar to a Pagani Zonda, only rotated 45° and out the bumper and not where the plate screws into the pretty panel.
http://media.fastestlaps.com/cj2at4z1llog/640x350m

The last real question I have about the High Comp setup is; do I have to have the head ported a lot to take advantage of 11.5-12.5 comp ratios? I intend on at least port matching and a polish, but anything more than that and I am going to have to send it to someone to be done (more money that I would prefer to not have to spend).

Any input, opinions, and advice is welcome, just please, rephrase your rude comments as informative criticisms.
Thanks,
~Squishy
 
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Alright guys/gals, I've had this del sol for about a year now (1995 Si)
Welcome to the site. i had a 94 si back in the day :)

175 whp is certainly possible on a d-series, but it's not easy to get, that's for sure.

First, I've heard before that the PG6 pistons limit your cam choice as the dome sits too close to the valves at TDC. If I run these pistons, is it safe to run a stage one Comp Cams camshaft?
I do not have experience with this combo, and the only way to be sure is to clay the motor. But, that's pricey as you would have already bought the parts.

If I were to go with the p29 pistons and go as High compression as I can (y8 .025) would I be fine if I had to settle for 91 octane gas somewhere in the boonies? Additionally, would the car still be streetable at 12.5:1? Same question on the Comp Cams Stage 1.

if you're tuned on 93 and need 91, the car will run ok... just keep it low in the rpm's/throttle and you won't detonate. it might be handy to keep a bottle of octane booster in the trunk on a trip, just in case.

Compression doesn't really drive streetability beyond the fuel requirements. Stage 1 cams are not very agressive at all. I'd probably argue that a stage 1 cam isn't going to be enough for you to obtain your power goal, however.

At what point do I have to upgrade my injectors?
you might not have to. 240cc is the size, and that's also the same size that the b-series engines use including the type R to make similar power goals.

That said, you will see on the dyno if you are running out of fuel or not.... and an upgrade may be necessary. I would not recommend skimping out on injectors. 1 mis fire can blow the whole thing up.
I know everyone is all gung-ho about Skunk2 products, but I'm still recovering from my GM days, and I've had great luck with Edelbrock, so that's my first choice on intake, I've also seen some OBX intakes with GIGANTIC plenums and straight runners, but they're for the obd2 d16's, can I adapt this easily? any opinions on performance??? And I am going to match the TB to the intake.
b-series parts will not work on a d-series... they are all different castings and runner spacing/etc. stick with z6 parts. y8, sometimes, may work too. The big IM's are usually for boosted applications. going all motor requires some runner science.

Exhaust isn't that important to me, I'm honestly going to buy an ebay 4-1 mani/downpipe with a test pipe (yay Iowa for no smog tests), and a 2.5" cat back, hopefully a twin-loop muffler (depends on the sound, I don't like fart cans or the lawn mower esque sounds they produce) Also considering a custom exhaust similar to a Pagani Zonda, only rotated 45° and out the bumper and not where the plate screws into the pretty panel.
http://media.fastestlaps.com/cj2at4z1llog/640x350m
it should be... exhaust is an important part of making power on these little guys. Sound is an issue, so avoid ebay junk or you'll sound like the ghetto civics. Get a quality item from a reputible brand and have a nice tone and power.

The last real question I have about the High Comp setup is; do I have to have the head ported a lot to take advantage of 11.5-12.5 comp ratios? I intend on at least port matching and a polish, but anything more than that and I am going to have to send it to someone to be done (more money that I would prefer to not have to spend).

You'll never make 175+ without extensive head work, and a larger cam than stage 1. Do you have to? No. but that really depends on how set you are on pushing limits.


As you list it with ~12:1 and a stage 1 cam and some bolt ons, you're MAYBE pushing 140whp on a good day if i had to guess. getting the next 35 horse out of it gets super expensive and requires hard-core work.
 
Wow, sweet, a lot of good information, but I should have stated that I'm not looking for 170 at the ground. I would be ecstatic if I got 150 to the wheels. Especially seeing as that's only going to cost me like $800 if I go all out with a stage 3 cam and upgraded valve springs. I also want to increase the redline to 7800-8000 depending on how much the new CR/flow changes the powerband
 
id go p29 route and the stock 240cc injectors will be fine n/a high comp even with a cam, id reccomend buying spare bottom end to build instead of tearing car apart, and port and polish isnt about just removing material you hinder flow , and you dont want a smooth surface in there glass beads up on smooth instead of staying mist, its going to be tough to make 150whp 170chp without a literally top to bottom build and supporting mods and aux fuel and tune , could spend 1/2 throw a turbo kit on it low boost 8< psi make more power and with a tune be more reliable and better mpgs , in racing NA is the most expensive way to go slow
 
I know you want to keep everything in the car "as-is", but the path of least resistance is really going to be a b-series swap. It's going to cost less, be faster to get running, and meet your goals. Especially with such a high miles d-series, I'd seriously consider swapping engines. Maybe you can find someone with a del sol with a stock b-16 that will let you drive it.
 
I know you want to keep everything in the car "as-is", but the path of least resistance is really going to be a b-series swap. It's going to cost less, be faster to get running, and meet your goals. Especially with such a high miles d-series, I'd seriously consider swapping engines. Maybe you can find someone with a del sol with a stock b-16 that will let you drive it.
I agree. Outside of a B16A3 shift linkage, it's pretty easy to locate B-parts and relatively cheap (especially a B18B1.....which is night and day feel compared to a D16Z6).
 
the linkage is not hard to find at all it just costs a few $$
http://passwordjdm.com/OEM-Honda-EG...erID=152387990&SessionID=mKT0E59VSWjKZdNnFdPk
http://www.jdmhondaswap.com/contents/en-us/p3648.html
http://www.swapshopracing.com/contents/en-us/p3648.html
https://www.jhpusa.com/store/pc/viewPrd.asp?idproduct=8232

i know you want to stay with the D series, but there really isn't any benefit. after doing all of the internal work you will not be saving much if any money, and that reliability you were trying to avoid a forced induction setup for is well out the window (not saying your high compression build cannot or will not be reliable, just that it is something of a crap shoot at that point), especially when a simple B18C or B16A swap would have all of the power you are looking for with OEM reliability, not to mention a much better transmission (with the option of a LSD)
https://www.hmotorsonline.com/motor-mall/b16a-92-95-or-96-98-sir-ii-complete-change-over-2
https://www.hmotorsonline.com/motor-mall/b18c-94-98-gsr-complete-change-over
when i got my swap from them years ago they included a del sol linkage for me
they are not the lowest priced shop by a long shot but their engines were always some of the nicest condition available (i am well out of this at this point so i cannot say if this is still the case)

i know this is not the info you are looking for at all, but i like to muddy the water whenever i can ;)
if you are hell bent on building a beast mode D series more power to you, im no help on that front but i respect your decision and look forward to the build thread
 
You should write out your goals for the car. Hp/tq, driving events, mpg, etc. Then write the number you want to spend on getting to said goals. After you do those two things, draw two columns. one for d-series and one for a b-series swap. Add up the cost of all the things you will need to do to reach your goals and see what happens.
 
Wow, this thread got more attention than I expected. Awesome.
First, I'm not going to do a b-swap, and for only one reason (beyond needing the special shift linkages).
I'm in the midst of fabricating mounting brackets for a Wago driveline. and I'm not shelling out the cost of a turbo for a b-d kit.
I am building a N/A High CR engine for the regular day-to-day and I'm going to be building a turbo set-up for end-goal, but I want to run the N/A in local autocross.
There are a couple autocross competitions that separate N/A from FI that I compete in from time to time.(very seldom, but I want to participate in the N/A races, there are a couple boosted fox bodies that dominate these two autocrosses)
I've only ever boosted one vehicle, and it didn't blow up, but I have a ton of experience running High comp setups on SBC and BBC engines.
That being said, you know how much tuning that takes? a damn screw driver and a couple jets. I'm not a tuning master, and with a high comp setup all I need to do is up the fuel pressure to match the needs of the new comp ratio, and have someone set a fuel map.
I would honestly love to swap in a b18 with a b16 vtec head, go all out on intake and exhaust, advance the ignition timing, run a hotter spark, 91 octane gas and put out the numbers I'm looking for, but there's no way I can justify paying the same price for the d-b kit as the whole swap. :/ if anyone has a kit they'll sell me for like 250, I'll do it.

As I stated, I'm going to build and tune a turbo z6, with which I'm going to only run 10 psi, unless I swap in vitara pistons. If I do that, I'm going to want stronger rods, and I'm REALLY sketched out about having to notch the block. But that is a project for the future.
One thing I've never had an issue with is the balance of the crank, assuming I'm going to keep the red-line down to 8k, do I need to worry about this?

I am assuming that the rt-4wd setup is still going to be 2 open diffs, and if I can upgrade those to LSD I will, but I can't imagine that's going to be easy to locate or cheap in any way, but I will be searching.

It's my birthday friday, so I'm going to clean the del sol up real nice, check my local pick-a-part and see if I can't score a new upper rad support so I can fix the panel alignment on the front end, and maybe cut out some patch panels to replace the quarters, because my passenger side quarter is at least 30% filler.

I'll take some pictures of the car and what I'm working with on the engine bay tomorrow before work, then after she's all nice and clean.

I live in the Iowa and the weather here is pretty inconsistent, but, if all goes well, I should be posting updates on progress on the build as early as the 27th.

And the two links for b-series engines, those are literally 3x+ the cost of what I'm looking at. The point of what this N/A build is going to be is taking advantage of the fact that I can rebuild an entire d-series 3 times before i hit b-swap prices.
 
the shift linkage is easy... cost of b > cost of engine build to make less power... who are we kidding this is hopes and dreams anyways , and bahhahahaha says is rt 4x4 swapping ? soo again you can fab that but are worried about shift linkage ?
 
There is a 99% chance this build doesn't get finished as you've outlined. But good luck and I hope that you prove us wrong.
 
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