4x4le

Like i said earlier, your boost level is a detrement to hp. 10-12 is all that turbo is going to be beneficial to. If you and your friend took boost readings in your hot pipe your pressure numbers would be vastly different.

But the main thing, the dyno yall used, especially the way they had it setup did not give you ANY data worth analizing. You wouldnt be putting this much thought into this topic if the printer was a 3 year old with a red and blue crayon would you? Because that might as well have been.

Even if a dynojet is setup the way it should be (which this one was not), the way smoothing works constantly "alters" the numbers it should be displaying. If the car is strapped down in a way that it rocks back and fourth like the straps are loose or springy it screws up smoothing. If your suspension squats and releases it screws up the smoothing. If the tires are bouncy ect.

You were given inconclusive data that you probably paid good money for. Sorry, thats a shame, and it was probably a new shop or new to them dyno and they dont know how to use it or dont care and they had a dyno day just to pay the bills.

Danger_Dorn

Thanks 4x4. Ill look around here to see about a better shop/dyno. Which dyno's are the good ones? FWIW my dyno run was free lol

4x4le

Dyno dynamics
Dynotech
Dynopac

cotbu

Don't be afraid to talk to the operator, they should go through a setup before they even make a pull, ask what's that for and why? Also be sweet, if they charge extra for boost or afr readings he/she might toss it in for free.

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rc1honda

How fresh was this rebuild. How was the break in done?

If you went straight to the dyno first thing that's where your problem may be as well. The pistons rings have to seal nice and snug before you see the real power of the motor.

Non fully seated rings and and a inefficient turbo maybe the cause for the low numbers.

JKTUNING

The amount of garbage in here about the use of a Dyno Jet is somewhat amusing, but alas I will leave that subject be.

Have you ever tried to verify you ignition timing, by putting the car in "timing mode" and checking to make sure you are within spec?

It is always the little things that will can get you and straight blaming it on the dyno for "inconclusive data", isn't the way you should be looking at this.

If you don't already have one, a Consult cable would be a great investment for this type of situation so you can check and verify what exactly is going on in your system.

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Danger_Dorn

I do have a consult cable and I use conzult and ecutalk. Usually ecutalk. The motor had a good 3k on it when I took it to the dyno. I'll try to take it again sometime and try out the things in this post. My timing is at 15btdc at idle in timing mode.

4x4le

If you want to discuss the uselessness of a dynojet Im down. Even the origonal designer/former owner did an interview with hotrod mag basicially shitting on it. When it came out there was nothing comparable to it but considering the technology of current cars, the precise requirements of tuning fuel injected turbo motors (not carbed n/a motors) and the types of dynos avabiable and their prices, dynojets are not relevant anymore. Anyone taking someones money to tune their engine should know this and if they dont I highly doubt their tuning ability.

cotbu

I've heard the dynojet I used was an eddy current dynojet, still reads the highest though, so that's where I get my bragging hp and tq figures from. I also never tune on a dynojet, but I was told the 442lcx? I used for power pulls, could be used for tuning, I said good to know, lol
I still say you need to use the same dyno at least twice, for power pulls. No debate from me I agree, 2¢

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JKTUNING

Like I said, I should leave this topic alone .. but your definition of "relevance" intrigues me.

Btw just to clear up any confusion, I am by no means a Dynojet "fan boy" .. I currently own and operate two in house chassis dynos and neither of them are Dynojets.

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inopsey

this is you leaving the topic alone? lol

JKTUNING

I said I "should" leave it alone .. but I am curious.

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Danger_Dorn

I did a compression test today...118 psi dry with a warm motor on the front 2 cyls. So Idk whats going on. My timing is right. I have a 1.8mm metal hg with arp headstuds. The motor has 3500 miles on it now after its rebuild. Any ideas? Ill try some oil in the cyls tomorrow. If it rises by 10 its bad rings and if not its bad hg/valves. The hg isnt blown from all that I can tell. I left my radiator cap off and saw no bubbles....

JKTUNING

Did you do the test at WOT?

What were the other two cylinders?

Do you have the resources to do a leak down test? This will show you a bit more than just a compression test alone.

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Danger_Dorn

I only did the first 2 because they were exactly the same 118. I didnt do them at wot now that I think about it. I just got in and cranked. Idk if anyone does a leakdown test around here.

Danger_Dorn

What are my options is my HG being too big is my problem? Full sytem upgrade (turbo, injectors, maf and tune?

ultimateirving

If you increased the head gasket thickness without milling the head, you may have lowered the compression ratio

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cotbu

C'mon do all cylinders, and do it correctly at least. I personally do a 3 fire with timing light, on all cylinders, when I check compression on an sr that comes in, then do a max compression test when I hook the battery to a charger/booster. My 3fire test is always higher than 120psi, but if it's not I'd recommend a leak down screw adding oil to the cylinders before doing other test. If you've just rebuilt the engine maybe light rehone and try a different break in method.

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Danger_Dorn

Cotbu- What do you mean by a 3 fire test? As far as a break in I took it on the highway and did some 3rd gear - half throttle pulls up to 5k and then let it go into vac back down to 2k a few times then soon after I just gave it hell.

Irving- I blew a hg, then did a rebuild so my head has been milled twice. Also I had the block milled. Would 1.8 mm hg really lower compression that much? idts....

Danger_Dorn

Also changing the head gasket is not an option unless its legitimately blown

4x4le

He means pull the injector clip on the cyl your checking, pull the coil and plug and put your compression check equipment in. Now start the engine.

cotbu

3 fires from the timing light. Did you check compression before and after break in? How did you know it was ready? By vacuum? If so what's the idle rpm and vac? That's not the best way but if you idle at 750rpm and pull 20inhg I'd say the rings are sealing, for sure.



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Danger_Dorn

I pull -16 to -18. Busy right now ill post later

jr_ss

118psi dry is low, regardless of what anyone says. Now if you have 118 across the board you're better off, but it's still not a good sign.

1.8mm head gasket is going to lower your compression quite a bit and I wouldn't be surprised if your closer to 8:1 vs the designed 8.5:1. How much was your head and block milled? You can calculate your actual compression number if you have those numbers. To fix your issue(I know I read), you need to install a new headgasket of 1.1mm thickness or have the block honed and new rings installed, if your comp numbers vary by 10-15%.

What cams are you running? -18in/hg isn't bad, -16in/hg is on the lower side, but can be affected by cams, which lower your actual vac.

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Danger_Dorn

Not arguing but I thought 16-18 inhg was pretty good? When I'm cruising and I let of the throttle into vac I get up to 24 inHg. Cams are oem. I did the compression test today with wot and got 135-140ish across the board so thats good. Idk how much they milled but does this compression seem right for a 1.8mm cosworth hg? As I said my head was milled twice and the block once.

jr_ss

While -16-18 isn't bad, -16 is still on the lower end of that spectrum. Typically you should be in the -18-21 area of vac especially on stock cams. I'm not saying you need to rebuild as there are other factors that can effect your vac readings.

A healthy motor is in the second vac reading I stated above. A motor with some serious cams will be lower, but that's still considered good vac because of the increase in duration and lift.

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4x4le

Yes, before you even consider a rebuild, check more than one map gauge, check more than one compression tester, and do a leakdown. A leakdown will point you in the direction of what is causing the low reading, hg, rings, valves ect. If it is rings it wouldnt hurt to run some conventional oil or some break in oil for a bit to try to seat the rings better, it is still a newer engine after all.

Danger_Dorn

Ok so update. I did a compression test when my motor was 170 degrees and WOT and got 135 on all 4. I replaced my thermostat the other day and now my car gets into the 190's so Ill give it another go to see if it yields higher numbers. From what I have read a 1.8 mm hg will lower compression from 8.5:1 to about 8.4 or 8.3 right?

Danger_Dorn

I also may try to retorque my headstuds since they may have moved during break in. ARP's 90ft lbs is what Ive done before but idk what the shop torqued it to

AJZax

RS-Enthalpy flew up to WA state, we dynotuned stock SR, it put 258whp at 14psi on a dynojet at 85F in summer. that's t25, 370s, walbro pump, exhaust, intake, and fmic (cxracing).

The objective of engine break-in is to load the piston-rings to they are pressed against the cylinder wall with pressure as to SEAT. I drove my car 18 miles to the dyno after an initial operating temperature "break-in". During these 18 miles it's all on throttle, engine decel, on throttle, engine decel. Put it on the dyno, and you could see it make more power every pull. FIrst like 270, then 330, then 440whp at 15psi. (SR gt3076r, E85). It was awesome to feel the car make more power as I drove it to the dyno also ^_^

When you first start your car you want to do on throttle, off throttle, first between the 2500-4500, then slowly expand that range, but keep out of 20psi+ hahah. After the idle oil change and the initial drive oil change, slap it on the dyno! Either it blows or it boosts!!! lol

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