1999 Yukon tuned

Taim · April 26, 2005

Hi there,

I just purchased a 99 Yukon and within a week installed borla headers, borla exhaust, hypertech tuner, and K&N series II intake. All is well with the install. However, I noticed a tapping noise coming from the engine under load. It wasn't there till I put the new headers on. What is this noise and how can I fix it? I am sure it is not coming from the headers...it sounds like exhaust valve slap (just a guess).

Also, what would be the next step in terms of more power? Is an edelbrock intake amnifold going to help or should I look at a crate engine (if so which one) or have I reached the peak of performance without blowing several grand. I am upgrading the braking system by adding slotted rotors and ebc pads soon. Braking should not be an issue.

I guess I should mention...the Yukon will be a street truck. I am not looking to lower it more than 2" but I do want a stiffer ride. Any input on any of these questions is greatly appreciated.

Thanks,

Taim.

zippy · April 26, 2005

here's a bit to start with. info

you may have a lifter tick, but my first guess would be an exhaust leak at or near the headers. doing an intake swap on that is a real bitch. i'd recomend going into transmission mods next. if horsepower is what you're looking for getting rid of that hypertech would be another good next step. without spending a rediculous amount of money i'd recomend a mild cam swap. you'll have to have the heads pulled and machined at the valve guides with new valve springs installed. there is easily a good 25hp gain in a cam swap if you go with the right parts without having to have ported cylinder heads. you're going to want to have it programmed right for your mods though. another swap to look into is a set of fastburn or edelbrock e-tec heads. you'll have a bit more room before you run out of injector. from there you'll want to do an intake swap and go with larger injectors. trust me getting power out of this setup isn't much problem.

snoman · April 26, 2005

Hi there,

I just purchased a 99 Yukon and within a week installed borla headers, borla exhaust, hypertech tuner, and K&N series II intake. All is well with the install. However, I noticed a tapping noise coming from the engine under load. It wasn't there till I put the new headers on. What is this noise and how can I fix it? I am sure it is not coming from the headers...it sounds like exhaust valve slap (just a guess).

Also, what would be the next step in terms of more power? Is an edelbrock intake amnifold going to help or should I look at a crate engine (if so which one) or have I reached the peak of performance without blowing several grand. I am upgrading the braking system by adding slotted rotors and ebc pads soon. Braking should not be an issue.

I guess I should mention...the Yukon will be a street truck. I am not looking to lower it more than 2" but I do want a stiffer ride. Any input on any of these questions is greatly appreciated.

Thanks,

Taim.

<{POST_SNAPBACK}>

I agree that the tick may be a exhaust leak next to head. On a Vortec engine a new intake will gain little but a set of deeper gear will really wake it up because you need to turn some RPM to make HP and gears will let you do it and put more power to ground to. If you have big rubber, slap in some 4.56's or 4.88's and you will think you installed a bigger motor.

zippy · April 27, 2005

just going to the L35 (4.3 HO engine) torque converter with the stock 3.73's and 275/50R17's i've pulled off a 2.04 60'. on the highway it's a pain though. at 70 it gets around 19mpg. at 85 it gets around 14mpg...i have had it to 131 so far though without the blower on it. the trans mods and programming were the biggest improvements so far in naturally asperated form.

snoman · April 27, 2005

just going to the L35 (4.3 HO engine) torque converter with the stock 3.73's and 275/50R17's i've pulled off a 2.04 60'. on the highway it's a pain though. at 70 it gets around 19mpg. at 85 it gets around 14mpg...i have had it to 131 so far though without the blower on it. the trans mods and programming were the biggest improvements so far in naturally asperated form.

<{POST_SNAPBACK}>

THe 4L60 has a 3.09 first gear and helps you get launched with a relatively tall gear but once you get up in the gears the advantage is gone. I had a old truck long ago with 4.10 gears and no OD that would do 120 and possible more but I never tried. It was turning about 5200 rpm at that speed but still had some left in it. Deep gears with a OD is a killer combo lower end and top end.

zippy · April 27, 2005

3.06 first. i know what you mean about the gear gain, but downside is driving it on the highway. at 70 i like to see 2200rpm or less. turning it any higher is just wasting fuel. going with 1000 or so more stall will pretty much always be more gain than say going from 3.42 to 4.10 gear.

snoman · April 27, 2005

3.06 first. i know what you mean about the gear gain, but downside is driving it on the highway. at 70 i like to see 2200rpm or less. turning it any higher is just wasting fuel. going with 1000 or so more stall will pretty much always be more gain than say going from 3.42 to 4.10 gear.

<{POST_SNAPBACK}>

High stall is no sub for gears and when a tranny is stalling it makes a LOT of heat and gets lower MPG in town too. There is a misconception about engine RPM though. A engine uses the least amount of fuel per HP hour produced when it is operated at or near its peak VE (Torque peak conisides with peak VE) What operated below it and under a good load as in a heavy truck with big tires MPG will suffer. Realistcally, a heavy 4x4 P/U with a small block and big rubber should turn about 2500 or so at 70 not 2200 as engien will be operating closer to its VE and will have more power availible in OD too (HP equals torque x RPM / 5252)

Taim · April 28, 2005

Guys thanks for the info,

zippy-ss-m, snoman, is the hypertech tuner really not that good of an idea? The shifting seens tighter and for that alone it seems worth it but if it drops power then to the trash it'll go.

I have another $1500-2000 to spend and have access to a machine shop, so the cam and head job sounds do-able. The question is then who and where do I get the parts from for a job like that.

On the issue of gears, I'm pretty much lost. The truck has to make it on the interstate at ~80 MPH and not use an excessive amount of fuel. (Just spent $60 on one freakin tank of gas.) I'd like to get 18-20mpg at those speeds. So, how much help in terms of 0-60 times am I looking at and how hard is it to replace the gears. (I have limited knowledge and workspace.)

Guys, thanks again.

Taim.

snoman · April 28, 2005

Guys thanks for the info,

zippy-ss-m, snoman, is the hypertech tuner really not that good of an idea? The shifting seens tighter and for that alone it seems worth it but if it drops power then to the trash it'll go.

I have another $1500-2000 to spend and have access to a machine shop, so the cam and head job sounds do-able. The question is then who and where do I get the parts from for a job like that.

On the issue of gears, I'm pretty much lost. The truck has to make it on the interstate at ~80 MPH and not use an excessive amount of fuel. (Just spent $60 on one freakin tank of gas.) I'd like to get 18-20mpg at those speeds. So, how much help in terms of 0-60 times am I looking at and how hard is it to replace the gears. (I have limited knowledge and workspace.)

Guys, thanks again.

Taim.

<{POST_SNAPBACK}>

I use a Hypertech 3 on my truck and I am happy with it and I can remove it and sell the tuner if I sell truck too which you cannot do with a Westers as it marries to VIN (Westers will give you a new tune for a new truck for a fee if you sell it but if you do not need it you are out the money for good) I like how easy it is to tweak for gear raito and tire size with Hypertech and get speedo dead on.

zippy · April 30, 2005

i have the trans coming into 4th gear at around 34 or so mph with the tcc coming in 2mph after that at city driving throttle. at cruising speeds the tcc is locked in almost all the time. this is under light throttle, but as long as you aren't driving it hard the trans temps never come over 160. we've tried it with a 3k pound trailer behind it and trans temps are around 185-210 depending on how hard you get on it. this is with no auxillary cooler. the hpp3 is a good upgrade from stock, but leaves alot to be desired on a modified truck let alone the trans settings still suck. this being shift timings, torque management, etc.

Taim · May 5, 2005

OK, an update...

Turns ot the ticking noise was due to the bolts on the far end of the header not being tightened down enough. Which means I blew out two gaskets in rapid succession( read two weekends). I was able to fix this by using Red RTV silicone sealant and a decent felpro exhaust gasket. It is a real pain to replace a header gasket 3 times!?! Well, a bead of sealant around both sides of the gasket and tightening everything down (correctly) seeems to have done the trick.

I am installing a new alpine head unit and some subs this weekend. So, I hope to start on the edelbrock 7516 intake manifold next weekend. I'm sure I'll have problems so till then.

Thanks.

zippy · May 6, 2005

we've had some experience with that here at the shop. are you trying to do something like this?

Taim · May 9, 2005

we've had some experience with that here at the shop. are you trying to do something like this?

<{POST_SNAPBACK}>

Yep, the intake I'm after is very similar.

It's the 7516 which is of the vortec performer rpm air gap variety.

I am debating if I should wait and do a comp cam replacement kit at the same time or not. If so, I need to save a bit more. If not, the 7516 should go in this or next weekend.

If you have any suggestions I'd really appreciate it.

Thanks,

Taim.

zippy · May 12, 2005

my partner in the shop did this one and can probably get you some important pointers that he learned along the way. just give him a call, i'll pm you the number.